How are months and years handled?

Adding months or years shifts the calendar month or year directly. As with calendars generally, the day may roll into the next month when the target month is shorter, for example 31 January plus one month.

Can I count backwards from a date?

Yes — choose "Subtract" to count days, weeks, months or years before the start date, for example to find a deadline that is 30 days earlier.

Does adding 7 days equal adding one week?

Yes. Adding one week shifts the date by exactly 7 calendar days, so "add 1 week" and "add 7 days" always produce the same result.

What happens when I add a month to the 31st?

The tool shifts the calendar month directly. When the target month has fewer days — for example 31 January plus one month — the date rolls forward into the following month, as standard calendar arithmetic does.

Is my date uploaded anywhere?

No — every calculation runs entirely in your browser and nothing is ever uploaded.

Add or Subtract Days Calculator

The Add or Subtract Days calculator shifts any date forward or backward by a number of days, weeks, months or years and shows you the resulting date and its weekday. It answers everyday questions like “what date is 90 days from now”, when a notice period ends, or when a subscription renews — without counting on a paper calendar.

How it works

You pick a start date, choose add or subtract, enter an amount, and select the unit. The tool then applies the shift directly to the calendar:

Days — moves the date by that many days.
Weeks — moves it by the amount × 7 days.
Months — shifts the calendar month, rolling into the next month if the target month is shorter.
Years — shifts the calendar year.

The result is shown as a full weekday-and-date string, so you immediately know not just the date but whether it falls on a working day or weekend.

Example

Start date 1 January 2026, add 90 days:

The result is 1 April 2026, a Wednesday (31 days in January + 28 in February + 31 in March = 90).

Input	Value
Start date	1 Jan 2026
Operation	Add
Amount	90 days
Result	Wed, 1 Apr 2026

Everything runs entirely in your browser — nothing is uploaded.