Date calculator: days between dates, add or subtract days
Days, weeks and working days between two dates, the date a number of days before or after a date, and the weekday of any date, with leap years handled.
Pick two dates. Today is filled in as the first.
How the days are counted
The calculator counts calendar days on the Gregorian calendar, including every 29 February that falls in the range (a leap year is divisible by 4, except century years, which must be divisible by 400; 2024 and 2028 are leap years, 2100 is not). The default count excludes the starting date and includes the end date, which is how "days until" is usually meant: from Monday to Wednesday is two days. Tick "both dates included" for the convention forms sometimes use ("the notice period runs from the 1st to the 15th inclusive"), which adds one.
Working days are Monday to Friday between the two dates, not counting public holidays, because those differ by state and by employer. Subtract your own holidays from the figure.
Worked examples
- From 17 September 2026 to 26 January 2027 is 131 days, 18 weeks and 5 days, with 93 working days (Monday to Friday).
- 90 days after 17 September 2026 is 16 December 2026, a Wednesday. A "90-day" visa or return window counted from arrival on the 17th therefore ends on 16 December, unless the issuer counts the arrival day as day one, in which case it ends on the 15th. When it matters, read the issuer's rule.
- From 14 May 1990 to 16 September 2026 is 13,274 days, the same figure the age calculator gives.
Where people go wrong
- Off by one. "Days between" and "days including both ends" differ by one, and a contract, an exam notification or a bank's interest calculation may use either. The calculator shows both conventions so you can match the document.
- Months are not units. "Three months from 31 January" has no single answer (30 April, or 1 May, or 28 April, depending on the rule). This page works in days; use the age calculator for calendar months.
- Excel and Google Sheets count days the same way as this page when you subtract two dates; their NETWORKDAYS function also excludes weekends but can take a holiday list, which this page does not.
- Time zones do not matter for whole dates, but a date typed as 17/9/2026 means 17 September in India and 9 May something in the US. The date fields here are unambiguous.