Date Subtract Calculator

Subtract days, weeks, months, or years from a date — for things like "what date was 90 days ago?" or "5 years before today".

Inputs

A positive whole number; use date-add for negative offsets.

Result

Loading calculator…
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General calculation reads

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Jordan Ellenberg - math thinking
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Scientific calculator (Casio fx-991EX)
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How to use this calculator

  • Pick the base date.
  • Enter how many days, weeks, months, or years to subtract.
  • Read the resulting earlier date.

About this calculator

Going backwards in the calendar is just as common as going forward — finding the date 30 days ago, the date 5 years before a deadline, the start of a 90-day window. This calculator subtracts the amount you specify from a base date, applying the same month-clamp rule as date-add.

Frequently asked

Is this just date-add with a negative number?+
Yes — under the hood it is the same calculation. The separate calculator exists because thinking "subtract 30 days from today" is more natural than "add −30 days".
How does subtracting months handle end-of-month dates?+
Same rule as date-add: clamp the resulting day to the last valid day of the target month. Mar 31 − 1 month → Feb 28 (or 29).
Can the result be a date in the past or future?+
It will be a date earlier than the base. If the base is in the future and you subtract a smaller amount, you might end up still in the future.
What is the maximum amount I can subtract?+
There is no software limit — you can subtract thousands of years. JavaScript dates handle a range of about ±275,000 years from epoch, far more than any practical use.
Why is the answer a different day of the week than I expected?+
Months and years are not multiples of 7, so subtracting in those units rotates the day-of-week. Use weeks if you want to land on the same day name.

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