Unit Converter 2025 | Metric ↔ Imperial, Temperature, Data & More

A dimension is a measurable physical quantity like length, mass, or time. A unit is a standardized reference for expressing that dimension—for example, meters and feet are both units of length. This converter supports 20+ categories (dimensions), each with multiple units from different measurement systems.

SI/Metric vs. US/Imperial Systems

The International System of Units (SI/Metric) uses base-10 scaling and standardized prefixes (kilo-, mega-, giga-) for consistency. Most countries use metric for science, engineering, and daily life. The US Customary/Imperial system (feet, pounds, gallons) evolved from historical British units and uses non-decimal relationships (12 inches = 1 foot, 16 ounces = 1 pound). The US is one of only three countries not officially metric, though scientific work worldwide uses SI.

Conversions between systems use exact or conventional constants. For example, 1 inch is exactly 25.4 millimeters by international definition (1959 treaty). However, some constants like pound-to-kilogram (1 lb = 0.45359237 kg) were originally empirical and standardized later for global consistency.

Scaling & Prefixes: kilo-, mega-, giga-, milli-, micro-

SI prefixes scale units by powers of 10. Common prefixes include:

• kilo- (k): 10³ = 1,000 (1 kilometer = 1,000 meters)
• mega- (M): 10⁶ = 1,000,000 (1 megawatt = 1,000,000 watts)
• giga- (G): 10⁹ = 1,000,000,000 (1 gigabyte = 1,000,000,000 bytes in SI)
• milli- (m): 10⁻³ = 0.001 (1 millimeter = 0.001 meters)
• micro- (μ): 10⁻⁶ = 0.000001 (1 micrometer = 0.000001 meters)
• nano- (n): 10⁻⁹ = 0.000000001 (1 nanosecond = 0.000000001 seconds)

These prefixes apply uniformly across dimensions. Converting within the same system (e.g., kilometers to meters, gigabytes to megabytes) is simple base-10 arithmetic. Converting between systems (e.g., miles to kilometers) requires a conversion factor.

Temperature: Special Case with Offsets (°C ↔ °F ↔ K)

Temperature conversions are unique because they involve both scaling and offset adjustments. Most dimensions (length, mass, volume) use simple multiplication: 5 feet × 0.3048 = 1.524 meters. Temperature requires formulas:

• Celsius to Fahrenheit: °F = (°C × 9/5) + 32
• Fahrenheit to Celsius: °C = (°F − 32) × 5/9
• Celsius to Kelvin: K = °C + 273.15
• Kelvin to Celsius: °C = K − 273.15

Example: 100°C (boiling water) = 212°F = 373.15 K. Notice 0°C ≠ 0°F (it equals 32°F), and 0 K (absolute zero) = −273.15°C = −459.67°F. Kelvin has no "degrees" symbol and no negative values—it's an absolute scale starting at absolute zero.

Precision, Rounding Modes & Significant Figures

This converter offers configurable precision (0-8 decimal places) and rounding modes (normal, floor, ceiling). Precision determines how many decimal places appear in results. Rounding modes control edge cases:

• Normal (half-up): 2.5 rounds to 3, 2.4 rounds to 2 (standard math rounding)
• Floor: Always rounds down (2.9 → 2, useful for material quantities that can't exceed available stock)
• Ceiling: Always rounds up (2.1 → 3, useful for minimum container sizing)

In engineering and science, significant figures represent measurement precision. If you measure 5.2 meters (2 sig figs), converting to feet gives 17.06 feet, but you should report ~17 feet (2 sig figs) to match original precision. This converter displays calculated values—you're responsible for rounding to match your measurement precision.

Exact vs. Conventional Constants

Some conversions use exact definitions (e.g., 1 inch = 25.4 mm exactly, defined by treaty). Others use conventional constants maintained by standards bodies like NIST (National Institute of Standards and Technology). For example, the speed of light is exactly 299,792,458 m/s by definition (the meter is now defined in terms of the speed of light), while the gravitational constant G is measured empirically and has uncertainty.

This converter uses NIST-standard constants where applicable, ensuring consistency with scientific and engineering practice. For critical applications (aerospace, pharmaceuticals, legal metrology), verify that our constants match your specific industry standards or regulatory requirements.

Data Storage: MB vs. MiB (Decimal vs. Binary Prefixes)

Data storage has two competing standards that cause widespread confusion:

• Decimal (SI) units: KB, MB, GB, TB use base-10. 1 MB = 1,000,000 bytes, 1 GB = 1,000,000,000 bytes. Hard drive manufacturers use this standard.
• Binary (IEC) units: KiB, MiB, GiB, TiB use base-2. 1 MiB = 1,048,576 bytes (2²⁰), 1 GiB = 1,073,741,824 bytes (2³⁰). Operating systems often display these but label them as "MB" and "GB."

This discrepancy explains why a "500 GB" hard drive shows as 465 GB in Windows: the manufacturer used decimal (500,000,000,000 bytes), but Windows displays binary GiB labeled as "GB" (500,000,000,000 ÷ 1,073,741,824 ≈ 465 GiB). This converter supports both standards—use MB/GB for marketing specs and MiB/GiB for actual memory calculations.

This converter is designed for both quick everyday conversions and advanced engineering calculations with batch processing. Follow these steps to get accurate results:

1. Select Category (Dimension)
   Choose the physical dimension you want to convert: length, mass, temperature, volume, area, speed, data storage, time, pressure, energy, or force. Each category contains units from multiple systems (SI, Imperial, specialized).
2. Choose From and To Units
   Select your source unit (e.g., miles) and target unit (e.g., kilometers). The dropdown menus are organized by system (Metric, Imperial, US Customary) and include common abbreviations (mi, km, ft, m). For temperature, you can convert between Celsius (°C), Fahrenheit (°F), and Kelvin (K).
3. Enter Value
   Type the quantity you want to convert. You can use decimal notation (123.45), scientific notation (1.23e5 = 123,000), or negative values where appropriate (temperatures can be negative). The calculator updates results in real-time as you type.
4. Adjust Precision & Rounding Mode (Optional)
   Set decimal precision (0-8 places) to match your needs. Use normal rounding for general use, floor rounding when you can't exceed a maximum (material cutting), or ceiling rounding when you need a minimum (container sizing, safety margins).
5. Enable Batch Mode for Multiple Conversions (Optional)
   Toggle batch mode to convert multiple values at once or convert one value to multiple target units simultaneously. Enter values as a comma-separated list (e.g., "100, 200, 500") or paste from a spreadsheet. Results display in a table format that you can copy or export as CSV.
6. Review Results & Inverse Factor
   The result displays in your chosen precision with the target unit symbol. Below the result, you'll see the conversion factor (e.g., "1 mile = 1.60934 kilometers") and the inverse (e.g., "1 kilometer = 0.621371 miles") for reference.
7. Use Quick Swap Button
   Click the swap/reverse button (⇄) to instantly switch From and To units. This is useful when you need to convert back and forth repeatedly (e.g., checking measurements in both inches and centimeters).
8. Copy or Export Results
   Click the result to copy it to your clipboard for pasting into spreadsheets, documents, or other calculators. In batch mode, export results as CSV for bulk processing in Excel, Google Sheets, or data analysis tools.

Pro Tip: For engineering work, use the precision slider to match your measurement instrument's accuracy. If your ruler measures to 0.1 mm, set 1 decimal place. For scientific notation input, use "e" notation: 3.5e6 = 3,500,000, 1.2e-3 = 0.0012.

1. Use the Right Category for Compound Units

Some quantities combine dimensions. Speed is length/time (miles per hour, meters per second). Density is mass/volume (grams per cubic centimeter). Pressure is force/area (pounds per square inch, pascals). Make sure you're converting within the correct compound category—converting MPH to meters won't give you m/s (you need the speed category).

2. Temperature: Don't Confuse Absolute and Relative Conversions

When converting a temperature value (e.g., "it's 20°C outside"), use the full formula with offset: 20°C = 68°F. But when converting a temperature difference or interval (e.g., "the temperature rose 10°C"), use only the scaling: 10°C change = 18°F change (multiply by 9/5, no offset). This converter handles value conversions—for differences, manually multiply: ΔF = ΔC × 9/5.

3. SI Prefixes Apply Universally Within a Dimension

Converting kilometers to meters? Multiply by 1,000 (kilo- = 10³). Megabytes to bytes? Multiply by 1,000,000 (mega- = 10⁶). Milliseconds to seconds? Divide by 1,000 (milli- = 10⁻³). Once you know prefixes, you can convert within SI instantly: 5 gigawatts = 5,000 megawatts = 5,000,000 kilowatts = 5,000,000,000 watts.

4. Data Storage: Know Whether You're Using Decimal or Binary

When converting file sizes or memory, check whether your source uses decimal (MB) or binary (MiB). RAM specs use binary (16 GiB = 17.18 GB). Hard drive labels use decimal (2 TB = 2,000 GB). Cloud storage often uses decimal. If you're calculating how many files fit on a drive, use the same standard as the drive manufacturer (usually decimal). If you're programming memory allocation, use binary.

5. Rounding Mode Matters for Engineering Tolerances

If you're cutting material and can't exceed a dimension (safety clearance, material limits), use floor rounding. If you're sizing a container and need to ensure everything fits, use ceiling rounding. For statistical analysis or when accuracy matters more than bias, use normal (half-up) rounding. Example: cutting 10-foot boards into 3.2-meter lengths. 10 ft = 3.048 m. You can cut 0 full 3.2 m lengths (3.048 ÷ 3.2 = 0.9525, floor = 0). Use floor to avoid overestimating material yield.

6. Batch Mode for Repetitive Conversions

If you're converting a list of measurements (e.g., recipe ingredients, parts dimensions, survey distances), use batch mode. Paste values from Excel/Sheets as comma-separated (or tab-separated) and convert all at once. Export as CSV to re-import into your original file. This is far faster and less error-prone than converting one at a time.

7. Unit Aliases and Abbreviations

Many units have multiple names or abbreviations. Length: m (meters), ft (feet), in (inches), yd (yards), mi (miles), km (kilometers), cm (centimeters). Volume: L (liters), gal (gallons), ml (milliliters), fl oz (fluid ounces), qt (quarts). This converter recognizes standard abbreviations—if unsure, check the dropdown or type the full name.

8. US vs. UK Imperial Units (Gallons, Tons, etc.)

The US and UK use different definitions for some Imperial units. A US gallon is 3.785 liters, but a UK (Imperial) gallon is 4.546 liters. A US ton (short ton) is 2,000 pounds, but a UK ton (long ton) is 2,240 pounds. A metric ton (tonne) is 1,000 kilograms (2,204.62 pounds). Always specify which system you're using—this converter labels units clearly (US gal, UK gal, metric ton).

9. Verify Constants for Critical Applications

For aerospace, pharmaceuticals, legal metrology, or safety-critical engineering, verify that our conversion constants match your specific standards (NIST, ISO, ASTM, regulatory requirements). While we use NIST-standard values, different industries sometimes use slightly different conventional constants or require specific rounding procedures mandated by regulation.

Unit conversions appear in countless real-world scenarios—from cooking and home improvement to international travel and professional engineering. Understanding when and how to convert units accurately saves time, prevents costly errors, and improves decision-making:

• Cooking & Recipe Scaling: International recipes use different measurement systems. European recipes list ingredients in grams and milliliters (metric); American recipes use cups, ounces, and tablespoons (imperial). Example: A French croissant recipe calls for 500g flour, 250mL milk, 100g butter. Converting to US units: 500g flour ≈ 4 cups (flour density ~120g/cup), 250mL milk ≈ 1.06 cups, 100g butter ≈ 7 tablespoons. Use mass (grams) for precision baking; volume works for casual cooking. When scaling recipes (doubling, halving), convert all measurements to same system first to avoid errors. This converter handles volume-to-volume (cups to mL) and mass-to-mass (ounces to grams); for volume-to-mass, use ingredient-specific density tables.
• Home Improvement & Construction: Building materials, tools, and plans often mix metric and imperial units. Example: You need to cover a 12 ft × 15 ft room (180 sq ft) with tiles sold per square meter. Convert: 180 sq ft ÷ 10.764 = 16.72 m². Order 17 m² of tiles (round up for cuts and waste). Lumber dimensions: US 2×4 studs are actually 1.5″ × 3.5″ (38mm × 89mm metric). When following international DIY plans, convert all measurements before cutting—errors compound quickly. Use ceiling rounding for material quantities (never run short), floor rounding for maximum dimensions that must fit spaces. Common conversions: 1 inch = 25.4 mm exactly, 1 gallon paint ≈ 3.785 liters, 1 pound = 0.454 kg.
• International Travel & Navigation: Road signs, fuel economy, and speed limits vary by country. US uses miles and MPH; most of world uses kilometers and km/h. Example: Speed limit sign shows 100 km/h in Canada. Convert: 100 km/h ÷ 1.60934 = 62 MPH. Rental car shows fuel efficiency 6.5 L/100km. Convert to familiar MPG: 235.215 ÷ 6.5 = 36.2 MPG. For aviation and marine navigation, distances use nautical miles (1 NM = 1.852 km = 1.151 statute miles), speeds use knots (1 knot = 1 NM/hour). GPS coordinates use degrees/minutes; 1 nautical mile = 1 minute of latitude. This converter handles all speed and distance units for seamless travel planning.
• Fitness & Health Tracking: Wearables and health metrics mix systems. Example: Your scale shows 75 kg; US doctor asks weight in pounds: 75 kg × 2.20462 = 165.3 lbs. Running app tracks 10,000 meters; you want miles: 10,000 m ÷ 1,609.344 = 6.21 miles. Temperature: European thermometer shows 38°C fever; convert to Fahrenheit: (38 × 9/5) + 32 = 100.4°F. Nutrition labels: European foods list energy in kJ (kilojoules); US uses calories: 1 calorie = 4.184 kJ. Medication dosing: mg/kg body weight prescriptions require accurate weight conversion. BMI calculators need consistent units (metric: kg and meters; imperial: pounds and inches). Use this converter to translate health data between medical systems and personal tracking apps.
• E-Commerce & Product Specifications: Online shopping from international retailers requires unit conversions. Example: Furniture listing shows dimensions 180cm × 90cm × 75cm. Will it fit your 6 ft × 3 ft space? Convert: 180 cm = 5.91 ft (fits 6 ft), 90 cm = 2.95 ft (fits 3 ft), 75 cm = 2.46 ft height. Electronics: EU power adapters list 230V 50Hz; US is 120V 60Hz—voltage converters needed. Storage devices: Hard drive advertised as 2TB (decimal) shows as 1.82 TiB (binary) in OS. Clothing sizes vary (US 8 = EU 38 = UK 12), but this converter handles length conversions for custom tailoring (chest 38 inches = 96.5 cm). Always convert before purchasing to avoid returns.
• Professional Engineering & Science: Technical work demands precise conversions with appropriate significant figures. Example: Aerospace engineer calculates thrust: 50,000 lbf (pounds-force) to Newtons: 50,000 × 4.44822 = 222,411 N. Pressure: 14.7 PSI (standard atmosphere) = 101,325 Pascals = 1.01325 bar. Torque: 100 ft-lbs = 135.582 Nm. Chemistry: molar mass calculations require grams to moles conversions. Physics: Energy in joules vs calories vs BTU. This converter uses NIST-standard factors; for critical applications (medical devices, aircraft, nuclear), verify constants match regulatory requirements. Set appropriate precision (6-8 decimals for engineering, 2-3 for general). Use batch mode to convert entire datasets from experiments or simulations.
• Agriculture & Land Management: Land area units vary globally. US farmland measured in acres; international agriculture uses hectares. Example: 640-acre section of land to hectares: 640 acres × 0.404686 = 259 hectares. Irrigation: gallons per acre vs liters per hectare. Crop yields: bushels per acre (US) vs tonnes per hectare (metric). Fertilizer application rates require volume and mass conversions. Fencing calculations: perimeter in miles vs kilometers. This converter handles area (acres, hectares, sq meters, sq feet), volume (gallons, liters, cubic meters), and length (miles, kilometers, feet, meters) for comprehensive land use planning.
• Automotive & Vehicle Maintenance: Car specs mix units depending on manufacturer origin. Example: Tire pressure 32 PSI to bar: 32 ÷ 14.5038 = 2.21 bar (European gauges). Engine displacement: 2.5 liters = 152.6 cubic inches. Torque specs: 90 ft-lbs = 122 Nm (metric socket wrenches). Fuel economy: 28 MPG (US) = 8.4 L/100km (European) = 33.6 MPG (UK). Oil capacity: 5 quarts = 4.73 liters. Ride height: 8 inches ground clearance = 203 mm. Always use correct units for torque specifications—over-tightening bolts by confusing ft-lbs and Nm causes expensive damage.

Pro Tip: For any real-world conversion, verify you're using the right category (length vs area vs volume vs mass). Determine whether precision matters (engineering yes, casual cooking no), and always round appropriately for the context—ceiling for material purchasing, floor for maximum dimensions, normal for statistical analysis. Batch mode saves time for large datasets; use it for recipe scaling, construction material lists, or converting spec sheets.

Even experienced professionals make unit conversion errors. Recognizing these common pitfalls prevents costly mistakes, safety hazards, and project failures:

• Using Linear Conversion Factors for Area or Volume: The most common error. Area factors are squared, volume factors are cubed. Example: 1 meter = 3.28084 feet (linear). Incorrect: 5 m² × 3.28084 = 16.4 sq ft (WRONG). Correct: 5 m² × (3.28084)² = 5 × 10.764 = 53.82 sq ft. Volume is worse: 1 m³ ≠ 3.28084 cu ft; it's 35.3147 cu ft (cubed factor). This error causes material shortages in construction (ordering 16.4 sq ft when you need 53.82 sq ft = 70% short). Always use the converter's Area or Volume category—it handles the squaring/cubing automatically. Never manually multiply linear factors for area/volume conversions.
• Confusing US vs UK (Imperial) Gallon, Ton, and Fluid Ounce: US and UK systems diverged centuries ago. US gallon (3.785 L) vs UK gallon (4.546 L) is a 20% difference—huge for fuel, chemical, or liquid volume calculations. US ton (2,000 lbs) vs UK ton (2,240 lbs) vs metric ton (2,204.6 lbs). Ordering 5 US tons of gravel when specs called for 5 UK tons = 10% shortage. US fluid ounce (29.57 mL) vs UK fluid ounce (28.41 mL). This converter labels units clearly (US gal, Imperial gal); always verify which system your source uses. For international projects, specify metric to eliminate ambiguity.
• Temperature: Forgetting the Offset (Using Only Scaling Factor): Converting temperature values (not differences) requires both scaling and offset. Incorrect: 20°C × 9/5 = 36°F (WRONG—freezing water can't be above freezing). Correct: (20 × 9/5) + 32 = 68°F. The +32 offset accounts for different zero points (0°C = 32°F). Exception: temperature differences (deltas) use only scaling. Example: 10°C increase = 18°F increase (10 × 9/5, no offset). Medical, HVAC, and scientific work require correct formulas. Use this converter's Temperature category to avoid manual formula errors.
• Mixing Mass and Volume for Different Substances (Density Confusion): Mass and volume aren't interchangeable without knowing density. 1 cup of water (236g) ≠ 1 cup of flour (120g) ≠ 1 cup of sugar (200g). Recipe conversions fail when assuming all substances have the same density. Correct approach: For liquids, volume-to-volume conversions work (cups to mL). For solids, use ingredient-specific density tables. "How many cups in 500g flour?" requires density: 500g ÷ 120g/cup = 4.17 cups. This converter handles mass-to-mass and volume-to-volume accurately; for mass-to-volume, you must supply density data separately.
• Ignoring Significant Figures (False Precision): Displaying more decimal places than your measurement's precision suggests false accuracy. Example: Measuring 5.2 meters with a tape measure (2 sig figs), converting to feet: 17.060368 ft (8 digits). Reporting should be ~17 ft (2 sig figs). False precision misleads stakeholders, causes manufacturing tolerances to be misinterpreted, and wastes time on unnecessary accuracy. Match output precision to input precision. This converter lets you set decimal places (0-8); choose based on source measurement quality, not arbitrary preference. Use 3 decimals for general work, 6+ for precision engineering, 0-1 for rough estimates.
• Forgetting to Square or Cube Conversion Factors for Compound Units: Compound units (speed, density, pressure, fuel economy) involve multiple dimensions. Example: Density in g/cm³ to lb/ft³ requires converting both mass and volume, then combining. Incorrect: 2.5 g/cm³ × (0.002205 lb/g) × (0.0328 ft/cm) = 0.00018 lb/ft (WRONG—dimensional analysis fails). Correct: 2.5 g/cm³ × (0.002205 lb/g) ÷ (0.0328 ft/cm)³ = 156 lb/ft³. Fuel economy (MPG to L/100km) is an inverse relationship: 30 MPG = 235.215 ÷ 30 = 7.84 L/100km, not 30 × some factor. Use the converter's dedicated categories (Fuel Efficiency, Density, Pressure) to avoid compound unit errors—they handle dimensional analysis correctly.
• Decimal vs Binary for Data Storage (MB vs MiB): Hard drives use decimal (1 GB = 1,000,000,000 bytes), operating systems often use binary (1 GiB = 1,073,741,824 bytes) but label it "GB". A 500 GB drive shows as 465 "GB" (actually GiB) in Windows. Calculating storage needs without knowing which standard causes confusion: buying a 1 TB external drive expecting 1,000 GB usable, getting 931 "GB" displayed. Always specify: use GB/MB for hard drive specs (marketing, manufacturers), GiB/MiB for RAM and actual memory calculations. This converter supports both; check labels carefully and don't mix standards mid-calculation.
• Using Wrong Rounding Mode for Context: Normal rounding works for statistics, but not all scenarios. Ordering materials: if calculations show 2.3 boards needed, rounding to 2 (normal) leaves you short—use ceiling (round up to 3). Maximum dimensions for clearance: if converted width is 2.9 meters but max allowed is 3 meters, floor rounding (2 meters) is safe; ceiling (3 meters) violates constraint. Always match rounding mode to context: ceiling for minimums and material orders, floor for maximums and capacity limits, normal for statistical analysis. This converter offers all three modes; select appropriately.
• Not Verifying Conversion Direction (Inverting Fractions): Simple algebra errors cause factor inversions. Example: Converting miles to kilometers, you need to multiply by 1.60934. Mistakenly dividing (10 miles ÷ 1.60934 = 6.2 km instead of 16.09 km) gives wrong direction. Similarly, PSI to Pascals multiplies by 6,894.76 (not divides). Pressure, torque, and energy conversions are particularly error-prone. Check: converted result should make intuitive sense (100 km > 100 miles because kilometers are smaller units). Use this converter to avoid manual arithmetic errors—it handles direction automatically. If doing manual conversions, write dimensional analysis to catch inversions.
• Assuming All "Miles", "Tons", or "Gallons" Are the Same: Context matters. Nautical miles (1,852 m) vs statute miles (1,609 m). Short tons (US, 2,000 lbs) vs long tons (UK, 2,240 lbs) vs metric tonnes (1,000 kg). Dry gallons vs liquid gallons. Survey miles vs international miles (differ by 2 ppm—negligible for most work, critical for precision surveying). Always verify definitions in technical specs. This converter uses international standards (statute miles, metric tonnes, liquid gallons) unless specified otherwise. For niche applications (maritime charts, land surveying), confirm exact definitions before converting.

The pattern across these mistakes: assumptions without verification, manual arithmetic errors, and context mismatches. Prevention strategies: (1) Always use dedicated conversion tools (this converter) instead of manual math for non-trivial conversions. (2) Verify units match source and destination requirements (US vs metric, decimal vs binary, absolute vs relative). (3) Check dimensional analysis (units cancel correctly). (4) Sanity-check results (order of magnitude, intuitive direction). (5) For critical applications (engineering, medical, legal), have a second person verify conversions. A $50 material shortage from conversion error can cost $500 in rush shipping and schedule delays. A 10% torque error can cause equipment failure. The time spent verifying conversions pays for itself many times over.

Output Format & Precision Display

Results display in your selected precision (0-8 decimal places) with the target unit symbol. For example, converting 5 miles to kilometers with 3 decimal places shows "8.047 km". The precision setting doesn't affect calculation accuracy (internally we use full floating-point precision)—it only affects displayed rounding.

Conversion Factor & Inverse Factor

Below your result, you'll see the conversion factor: "1 mile = 1.609344 kilometers". This is the multiplier used in the conversion. You'll also see the inverse: "1 kilometer = 0.621371 miles". The inverse is useful for quick mental checks (if 1 km ≈ 0.62 mi, then 10 km ≈ 6.2 mi, 100 km ≈ 62 mi).

Scientific Notation for Very Large or Small Values

For extremely large or small numbers, results display in scientific notation. Example: 1 light-year = 9.461e15 meters (9.461 trillion meters). This prevents unwieldy displays like "9,461,000,000,000,000". You can input values in scientific notation too: type "1.5e6" for 1,500,000.

Temperature Result Interpretation

Temperature results use the full offset formula. Converting 0°C shows 32°F (not 0°F), because the formula is °F = (0 × 9/5) + 32. Negative temperatures are common (−40°C = −40°F is the same temperature; below that, Celsius is "warmer" than the Fahrenheit number). Kelvin never goes negative because it's an absolute scale starting at absolute zero (0 K = −273.15°C).

Batch Mode Output Table & CSV Export

In batch mode, results display as a table with columns: Original Value, Original Unit, Converted Value, Converted Unit. You can copy the entire table to paste into spreadsheets, or export as CSV for data analysis. CSV format uses commas to separate columns and includes a header row.

Unit Symbol Normalization

This converter normalizes unit symbols to standard abbreviations. You might type "kilometers", but the result shows "km". Fahrenheit appears as "°F" (with degree symbol), Celsius as "°C", Kelvin as "K" (no degree symbol). This follows international standards (SI, ISO) for scientific notation.

Rounding Effects on Final Value

Rounding only affects the displayed result, not intermediate calculations. If you convert 10 miles to kilometers (16.09344 km), then convert that result to meters, we calculate 10 mi → m directly (16,093.44 m), not 16.09344 → m (which would lose precision). This prevents cumulative rounding errors in multi-step conversions.

Constants Source: NIST & ISO Standards

Conversion factors come from NIST Special Publication 811, ISO standards, and international treaty definitions (like the 1959 international yard/pound agreement). We update constants when standards bodies issue revisions. For the most critical applications, check that the version date of constants matches your requirements.

When Results Look "Wrong": Common Confusions

Why isn't 0°C = 0°F? Because they have different zero points. 0°C is freezing water, 32°F is freezing water.
Why does my 500 GB drive show as 465 GB? Manufacturer used decimal GB (base-10), OS shows binary GiB labeled as "GB".
Why is 1 US gallon ≠ 1 UK gallon? Different historical definitions. Always specify which gallon.
Why does 1 inch = 2.54 cm exactly, not 2.54000001? It's an exact definition by international treaty.
If a result looks unexpected, double-check that you're using the right category, the right system (US vs UK vs SI), and the right conversion type (absolute vs relative for temperature).