Biology & Lab Research

Pick a tool by where you are in the experiment

Organized by workflow phase rather than alphabetically. Use the cluster that matches your current step.

"I'm planning a cell culture experiment."

Start with the cells-per-vessel seeding math for your target confluence (6-well, 96-well, T75, custom flask). For media recipes and supplement timing, the media prep planner handles serum-free additions and glutamine handling. The Lipofectamine and PEI volume math covers transfections, and stock-to-working solution prep runs the reagent dilutions you set up in parallel.

"I'm setting up a PCR or qPCR plate."

The master mix sizer with overage handles any plate count for both PCR and qPCR. The primer Tm and design-flag checker catches GC clamps, homopolymer runs, and self-dimers before you order from IDT. After the plate runs, the ΔΔCt fold-change calculator applies Pfaffl efficiency correction. For copy-number inputs, the ng/µL to nM converter covers dsDNA, ssDNA, and RNA.

"I need to quantify cells, DNA, or protein."

For bacterial or yeast cultures, the OD600 to cells/mL converter uses species-specific factors (E. coli, S. cerevisiae, or custom). For absorbance-based protein and nucleic acid quant, the A = εcl solver handles any three-known one-unknown case plus calibration curves. Nucleic acid molarity for mass-to-molarity conversion, circular plasmid copy number for cloning math, and the hemocytometer cell-count calculator for live-cell totals with viability.

"I need to plan a dilution or solution."

For stock-to-working-concentration math, the single and multi-step dilution planner sizes intermediate volumes with overage for pipette dead volume. For plate-count microbiology, the serial dilution and CFU/mL back-calculator runs the math the other direction: serial 1:10 transfers down a row, then back-calculate from colony counts using the 30-300 countable rule.

"I'm analyzing experimental data."

The Michaelis-Menten fitter returns Km, Vmax, and kcat with Lineweaver-Burk and Eadie-Hofstee plots alongside as fit-quality sanity checks. The enzyme inhibition visualizer compares competitive, noncompetitive, and uncompetitive curves for Ki estimation. The 4PL EC50 estimator covers agonist and antagonist data, and the doubling-time fitter handles growth curves including biphasic edge cases.

"I'm doing lab logistics or storage."

The -80°C box-indexing helper lays out grid positions and keeps the LIMS-vs-physical-location separation clean across shelf rotations. The hybridization Tm estimator handles probe and primer Tm under specific salt and formamide conditions. The RPM-to-g converter sits next to every protocol that moves between rotors.

"I need a specialty calculation."

For event-count prep, the flow cytometry sample sizer handles doublet-discrimination and reservoir overage. The ELISA plate map and standard curve planner covers 96-well layout and auto-generates the dilution series. The Western blot loading volume calculator sizes the SDS-PAGE master mix. The CRISPR RNP planner scales between 96-well screens and 6-well validation. The first-order PK half-life calculator covers the textbook math, educational use only.

Lab math you do daily: the units and conversions

Molarity (M, mM, µM, nM, pM)

Each step is a factor of 1000. A 1 M solution holds one mole of solute per liter, and that's the unit a biochemist usually wants for stoichiometry and reaction setup. mM is normal for buffers, µM for enzyme assays, nM for primers and probes, pM for the high-sensitivity end of ligand-receptor work. Shift the decimal three places per step.

Mass concentrations (mg/mL, ng/µL, ng/L)

What labs actually read off a NanoDrop or fluorometer. ng/µL is the working unit for DNA and RNA after extraction (Qubit returns this directly). mg/mL is standard for purified protein after BCA or Bradford. Conversion to molarity needs molecular weight, which is why MW lookup matters before any stoichiometry math.

C₁V₁ = C₂V₂

Stock concentration times stock volume equals target concentration times target volume. It assumes ideal mixing and no volume change on combination, which holds for aqueous dilutions below about 1 M and breaks for concentrated organic solvents like DMSO or chloroform. The equation is fine below 1 µL target volume. Your pipettor usually isn't.

Log dilutions

Serial 1:10 keeps each step compact and the per-dispense pipette error small. Serial 1:2 doubles the step count to reach the same dilution factor, which compounds error. Across n serial 1:10 steps, the dilution factor is 10ⁿ, so 6 steps land at 10⁻⁶ of stock. That's the number plate-count microbiologists work with constantly.

OD measurements

OD600 for cell density, OD260 for nucleic acid, OD280 for protein, A595 for Bradford. Classical spec work assumes a 1 cm cuvette path. Microplate readers run at ~0.27 cm and need a path-length correction. OD is not a direct cell count: the conversion factor depends on species and growth phase, which is what catches people on the first overnight reading.

Cells/mL to cells/well

A 96-well has 0.32 cm² per well, a 6-well has 9.6 cm², a T75 has 75 cm². Per-area seeding density scales by surface area, not by media volume, which is why scaling a transfection between formats needs a ~30x factor between 96-well and 6-well and not a media-ratio factor.

g-force vs RPM

Centrifuge rotors are rated by RPM, but protocols specify g-force because g is what actually sediments the sample. RCF = 1.118 × 10⁻⁵ × r × RPM², with r in centimeters. Rotor radius is the bridge: same RPM on different rotors yields different g, so recompute on every rotor swap.

fmol and copy number

fmol is 10⁻¹⁵ mol, which works out to about 6.022 × 10⁸ molecules. Copy number per µL falls out of (mass / MW) × Avogadro's number, scaled to your volume. A 500 bp dsDNA amplicon at 100 ng/µL (MW 330,000 g/mol) is roughly 1.8 × 10¹¹ copies/µL. That's the math behind a qPCR standard curve.

How the 26 tools cluster on a normal bench day

Methodology, sources, and editorial stance