Date Calculator
Add or subtract days from any date, or find exactly how many days fall between two dates.
30 calendar days after September 11, 2026
This tool does date arithmetic so you do not have to. Add or subtract any number of days from a date, with an option to skip weekends, or count the total days between two dates.
Deadline in 45 working days? Project starting 90 calendar days from today? Contract running for 6 months? This covers it.
How we work it out
Calendar day mode adds or subtracts the exact number of days from the start date, including weekends. Working day mode counts forward or backward, skipping Saturday and Sunday. The days-between mode gives total calendar days between the two dates, plus the equivalent in working days and full weeks.
Questions
Does it include bank holidays?
No. Working day mode skips weekends only. Bank holidays vary by country and region, so you would need to subtract those manually.
Does the start date count as day one?
No. The count starts the day after the start date. So adding 1 day to Monday gives Tuesday, not Monday itself.
Deadline not for a while yet.