Date Calculator
Find the exact number of days, weeks, months and years between two dates, or add and subtract time from any date — useful for deadlines, events and planning.
Choose a start and end date to see the exact difference.
How to Use the Date Calculator
- 1Switch between the “Date Difference” and “Add / Subtract” tabs depending on what you need.
- 2For date difference, pick a start and end date to see the exact gap between them.
- 3For add/subtract, pick a start date, an amount, a unit (days, weeks, months or years), and choose Add or Subtract.
- 4Your result updates instantly as you change any input.
How Date Calculations Work
For date differences, the calculator counts complete years, then complete months in the remainder, then leftover days — the same calendar-accurate method used across every date tool on this site, so a February-to-March span is measured correctly whether or not a leap year is involved.
Worked example: from 10 January 2026 to 25 March 2026 is 2 months and 15 days, or 74 total days. Adding 6 weeks to 10 January 2026 lands on 21 February 2026 — the calculator rolls over month boundaries automatically rather than assuming every month has the same length.
Calendar days vs business days: this calculator counts every calendar day, including weekends. If you need only working days — for project timelines or delivery estimates — use the dedicated Business Days Calculator instead, which excludes Saturdays and Sundays.
Frequently Asked Questions
Formula and figures on this page were checked against official sources as of August 2026. See our editorial process. This tool is for informational purposes only and isn't financial, tax or medical advice.