Calculate the difference between two dates, add or subtract days, months, or years, and find future or past dates.
This tool allows you to perform various date calculations quickly and easily. Whether you need to find the difference between two dates, add or subtract days, months, or years, or find future or past dates, this calculator has you covered.
Select an operation: find the difference between two dates or add/subtract a duration from a date. Use the calendar to pick dates and input the amount and unit for calculations.
Work out the number of days, weeks, months and years between two dates, or add and subtract a period from a starting date to find the resulting date. It uses calendar arithmetic, so leap years and different month lengths are handled correctly.
Date maths is deceptively fiddly by hand: February changes length, some periods should count the start day and some should not, and "three months" from the 31st lands on different days depending on where you start. Letting the calculator do it removes those errors from deadlines, contracts and planning.
Total days = later date − earlier date (the start day is not counted, the end day is)Weeks = total days ÷ 7Years, months, days = full calendar years, then full months, then leftover daysAdd/subtract days = move that many calendar days from the start dateAdd/subtract months = same day-of-month in the target month, clamped to the last day if it does not exist250 days. That is 35 weeks and 5 days, or about 8 months and 7 days.
13 November 2026. Ninety calendar days, weekends and holidays included — useful for return windows and payment terms.
28 February (or 29 in a leap year). There is no 30 February, so the date is clamped to the last day of the month.
7 years, 5 months, 27 days — full years first, then the remaining months and days.
Check in 4 July, check out 9 July: the difference is 5 days, which equals 5 nights. Counting both dates would give 6, which is why nights and days differ.
The difference counts the end date but not the start date, so 1 March to 4 March is 3 days. This matches how nights, notice periods and interest days are usually counted.
29 February is a real day in the count. A one-year span that crosses a leap day is 366 days rather than 365.
February has no 31st, so the result is clamped to 28 February (29 in a leap year). Adding another month returns to the 28th or 31st depending on the tool's setting.
The main difference is in calendar days. For business-day counts, subtract weekends and public holidays for your country separately.
Months are not all 30 days. The calculator counts real calendar months, so the two figures will differ for most spans.
Yes. All date maths happens in your browser.