How Long Since / Until
Calculate exactly how much time has passed since a past event or how much time remains until a future date. With live updates and both calendar and duration views.
Event Details
Frequently Asked Questions
Time Since or Until Any Event
Calculate exactly how much time has passed since a past event or how much time remains until a future date. Perfect for anniversaries, countdowns, and more.
Past Events
See how long since historical moments or personal milestones
Future Events
Count down to birthdays, holidays, or upcoming deadlines
Live Updates
Watch the seconds tick by in real-time
Tip: Use preset events like "Moon Landing" or "Y2K" for quick calculations, or enter any custom date and time.
Frequently Asked Questions
Understanding Time Calculations
Related Time & Date Tools
Explore more tools for working with dates, times, and calendars.
Date Difference Calculator
Calculate total days, weeks, months between any two dates with calendar or business day options.
Age Calculator
Calculate exact age in years, months, days, and find your next birthday.
Countdown to Date / Event Builder
Create a live countdown timer to any date and time.
Leap Year & Calendar Helper
Check leap years and compute day of week, week number, day of year, and more.
Time Zone Meeting Planner
Find overlapping availability windows for meetings across multiple time zones.
Business Days Calculator
Count business days between two dates, excluding weekends and optional holidays.