Date Calculator
Two date jobs on one page: find how much time lies between two dates, or add and subtract days from a date to land on another. The second mode takes negative numbers too, so counting backwards from a deadline works exactly as well as counting forwards.
How to calculate a date
- Choose Difference or Add/subtract days.
- Enter your date(s).
- Read the result below.
When you'd use this
- Deadlines — Finding the date thirty days from now, or working back from a due date.
- Notice periods — Working out a last working day from a resignation date.
- Project planning — Counting the days available between a start and a delivery date.
- Documents and validity — Checking when a period of validity actually ends.
Good to know
- Two modes — Difference measures the span between two dates. Add / subtract days moves a date forwards or backwards.
- Subtract with a negative number — There is no separate subtract button — enter a negative figure in the days box to count backwards.
- Leap years are handled — Real calendar days are counted, so February and leap years are treated correctly.
- Every day counts equally — The result includes weekends and holidays, which vary by country and are not built in.
Frequently asked questions
Can I subtract days instead of adding?
Yes — in Add/subtract mode, type a negative number to go backward from the start date.
Does the difference count include both dates?
The difference is the number of days between the two dates, not counting either endpoint twice.
How do I count backwards from a date?
Use the add mode and enter a negative number of days — entering −45 gives you the date 45 days before the one you chose.
Does it skip weekends or public holidays?
No. It counts calendar days, since holidays differ by country, state and year. For working days you would need to adjust the result yourself.
Is the end date included in the difference?
The difference is the number of days between the two dates. If your situation counts both the first and last day, add one to the result.