Date Difference Calculator
Find the exact time between two dates — in days, weeks, months, and years. Also calculates working days.
Enter both dates to see the difference.
How to use Date Difference Calculator
The date difference calculator computes the exact duration between two dates in multiple units simultaneously: total days, weeks and days, months and days, years/months/days, and working days. It handles past and future dates equally, indicates the direction (start before or after end) and includes a copy button. This tool is ideal for calculating ages, contract durations, project timelines and time since events.
- Enter the start date.
- Enter the end date, or use "Today" to calculate from the start date to now.
- The difference is calculated instantly in all unit formats.
- Use "Set End = Today" for age or time-since calculations.
Your data never leaves your device — 100% private processing.
How date differences handle months and years
Total days is straightforward. Months and years are trickier: from January 15 to March 10 is 1 month and 23 days, not exactly 54 ÷ 30. This calculator uses calendar arithmetic — subtracting year-by-year, then month-by-month, then day-by-day — matching how humans intuitively count time rather than simply dividing total days by 30.44.
Working days vs calendar days
Working days exclude weekends (Saturday and Sunday) from the total. This is useful for project timelines, SLA calculations and deadline planning. A 14-calendar-day period contains 10 working days if no holidays fall within it. For holiday-aware calculations, use the Business Days Calculator.
Glossary
- Calendar days
- All days counted inclusively including weekends and holidays.
- Working days
- Monday–Friday days excluding weekends.
- Epoch
- Reference point for timestamps; commonly January 1, 1970 (Unix).
Related reading
Frequently Asked Questions
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Why use Date Difference Calculator?
- Handles timezone conversions and DST automatically
- Supports date arithmetic across years and leap years
- ISO 8601 and human-readable output formats
- Works for historical and future dates with full accuracy
Common use cases
- Calculate how many days until a project deadline
- Find the day of the week for a date in the past
- Convert meeting times across different time zones
- Calculate age from a date of birth
- Add or subtract business days for contract terms
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