Date Calculator
Find the difference between two dates or add/subtract days, weeks, months, and years from a date.
- Free forever
- Instant results
- Private — runs in your browser
How to use the Date calculator
Date difference: pick a start and end date to get the gap in days, weeks, months and years, plus the number of business days (Monday–Friday). Tick “include end date” if you are counting both the first and last day, e.g. for a hotel stay or a leave request.
Add / subtract: choose a date and add or subtract days, weeks, months, years or business days to find a deadline, due date or anniversary.
Formula
Days between = (End − Start) in whole calendar days. Dates are compared at midnight UTC, so daylight-saving changes never shift the result.
Adding months keeps the same day of the month, or the last day if it doesn’t exist (31 January + 1 month = 28/29 February).
Business days skip Saturdays and Sundays; public holidays are not excluded.
Frequently asked questions
Does this account for leap years?
Yes. Every calculation uses real calendar dates, so 29 February and months of different lengths are handled exactly.
Is the end date included in the count?
By default no — the result is the number of days from the start date up to the end date, the same way you would count nights. Tick “Include end date” to count both days, which adds one.
Are public holidays excluded from business days?
No. Business days here are Monday to Friday only, because public holidays differ by country and region. Subtract any holidays that fall in your range manually.
What happens when I add one month to 31 January?
You get the last day of February (28th, or 29th in a leap year). The calculator never rolls over into the next month.