Softonic

Date Add and Subtract

Step 1 / 4 Resulting date
Next

Pick a start date, choose a direction (add or subtract), enter an amount in days, weeks, months or years, and the tool returns the resulting date, formatted with the weekday and month names in your language. Handy for working out contract end dates, payment windows, warranty expiry, flight visa windows or a personal ‘90 days from today’ deadline, without having to flip through a calendar.

How to add or subtract from a date

  1. 1

    Pick the start date

    Any calendar date between 1900 and 2100 works. Today is filled in by default.

  2. 2

    Choose the direction

    Add moves the date forward; subtract moves it backward.

  3. 3

    Enter amounts

    Combine days, weeks, months and years in a single operation. Weeks = ×7 days internally.

  4. 4

    Read the resulting date

    The output shows the resulting calendar date, formatted with the weekday and month names in your language.

Calendar arithmetic is trickier than it looks

Adding days is trivial: shift the Julian day number. Adding months and years is where every implementation has to pick a behaviour for edge cases. This tool follows the ISO 8601 convention used by most modern languages: when the target month has fewer days than the source, the result clamps to the last valid day.

  • 31 January + 1 month → 28 February (29 February in a leap year).
  • 31 March + 1 month → 30 April.
  • 29 February 2024 + 1 year → 28 February 2025 (not 1 March).

Common date-math tasks

Use case Rule of thumb
Net-30 invoice Issue date + 30 days
Net-60 or Net-90 invoice Issue date + 60 or 90 days
Schengen 90/180 rolling window Entry date + 89 days for the last legal day
US ESTA validity Approval date + 2 years
Standard passport validity Issue date + 10 years
Probation period Start date + 3 or 6 months
Warranty (consumer) Purchase date + 1 or 2 years

Weeks ≠ months

A week is always 7 days. A month is 28, 29, 30 or 31 days depending on which one. Add “3 weeks” to an arbitrary date and you always move 21 days. Add “3 months” and you might move anywhere from 89 to 92 days. Pick the unit that matches the contract or regulation you are working with.

Business days vs. calendar days

This tool counts calendar days (every day of the week). If a contract says “within 10 business days”, weekends and public holidays do not count, use a business-days calculator instead, and remember that public holidays depend on your jurisdiction.

Frequently Asked Questions

It clamps to the last day of the target month, which is 28 February (or 29 in a leap year). This matches the behaviour of modern date libraries like Python datetime, PHP DateTime and JavaScript Temporal.

No. This tool works in calendar days, weeks, months and years. Weekends and public holidays are included. For business-day math use the dedicated business-days calculator.

The calculation is purely date-based, so no time zone applies. Midnight and 23:59 on the same day both produce the same result.

Yes. The tool applies years first, then months, then weeks, then days, matching how most people think about “2 years and 3 months and 10 days from today”.

No. Your dates and amounts are sent to our servers only to compute the result as part of the page interaction, and they briefly appear in the page link while you move through the tool’s steps. They are not stored, logged or shared with anyone.

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Tool available in other languages