Date difference calculator

Two calculations in one

Between two dates gives the exact time from one date to another: in years, months and days, and as total days, weeks, months and hours. It also shows how many of those days are working days. Add or subtract works the other way: start from a date, add or take away years, months, weeks and days, and see the date you land on, with its weekday.

A days between dates calculator and date calculator: count how many days between two dates, or add days to a date.

How the days are counted

The count runs from the start date to the end date, not including the end date. Monday to Friday is 4 days, the same way you’d count nights in a hotel. For events where every day counts, such as a 5-day course from Monday to Friday, switch on Include the end date to add one.

Months are calendar months, not 30-day blocks. From 15 March to 15 May is exactly 2 months; from 15 March to 20 May is 2 months and 5 days. From 1 January to 1 March 2026 is 59 days, which is also exactly 2 months.

Adding months to the end of a month

When you add months to the 29th, 30th or 31st and the target month is shorter, the result is that month’s last day. 31 January plus one month is 28 February (29 in a leap year). Years and months are added first, then weeks and days, so 31 January plus 1 month and 1 day is 1 March.

Common uses

• How many days until a deadline, exam or trip, or since a past event.
• Notice periods, probation and contract end dates, such as 90 days from a joining date.
• Visa stays, warranty and subscription expiry, medicine courses.

For deadlines that count only business days, with public holidays taken out, use the working days calculator. For a live countdown to a single date, try days until, and for someone’s exact age, the age calculator.