Date difference calculator

How many days until a holiday, how long a project took, how many weeks a pregnancy has progressed or how many months remain on a contract: all of these are questions about the difference between two dates. This calculator gives the answer as a calendar breakdown (years, months, days) and as totals in weeks, days and hours.

How to use it

1. Choose the start date and end date.
2. Read the difference as years, months and days, and as total weeks, days and hours.
3. Switch modes to add or subtract days, weeks or months from a date instead.

Worked example

From 1 March 2024 to 27 October 2026:

• Calendar difference: 2 years, 7 months, 26 days.
• Total: 970 days, which is 138 weeks and 4 days, or 23,280 hours.

The leap day 29 February 2024 is not included because the range starts on 1 March 2024; starting from 1 February 2024 would include it.

Inclusive vs. exclusive counting

By default the difference counts the days between dates, so Monday to Wednesday is 2 days. If you need to count both the start and end days, for example for a hotel stay or event duration, add one day. Check which convention your contract, policy or form uses.

Why months are tricky

Months vary from 28 to 31 days, so a difference expressed in months and days depends on the starting month. That is why 1 January to 1 March is exactly 2 months but only 59 days, while 1 July to 1 September is also 2 months but 62 days. Use total days when you need an unambiguous number.