Subtract days from date

Starting date

Amount

Unit

Direction

Resulting date —

30 days before

About that date

ISO form —

Day of the week —

Day of the year —

ISO week —

Note Enter a date

Same clamping rules in reverse

Counting backwards works the same way as forwards. Thirty days before 2 March 2026 is 31 January. Subtracting one month instead gives 2 February, because months keep the day number rather than a fixed count.

How to count back from a date

1 Set the date you are counting back from.

2 Enter the amount and unit.

3 Read the resulting date and its weekday.

4 Switch direction if you meant to go forwards.

Counting backwards is what deadlines actually require. A filing due on a fixed date with a 21-day notice period needs the date 21 days before, and getting it wrong by a day is the difference between compliant and not. Where the period is defined in working days, use the business-day version — the two diverge quickly, since 21 working days is over four calendar weeks.

Questions

What date was 30 days ago? −

Leave the date as today and set 30 days — the result is shown with its weekday.

Is subtracting a month the same as 30 days? +

What about 31 March minus one month? +

Does it skip weekends? +

Can I go back years? +

Was this tool any good?

INTERNAL SIGNAL ONLY · WE USE IT TO FIND TOOLS WORTH REBUILDING