Add or Subtract Days from a Date

How it works

This tool shifts a starting date forward or backward by a chosen amount. Pick a start date, choose whether to add or subtract, enter a number, and select the unit: days, weeks, months or years. The calculator returns the resulting calendar date.

For days and weeks the math is a straight offset, so crossing month or year boundaries is automatic. For months and years the calculator follows calendar rules: adding one month to 31 January lands on the last day of February (28 or 29), and adding a year keeps the same month and day. This matches how people normally think about "one month from now" rather than a fixed 30-day block.

Examples

Example: 30 days from today

Starting 11 August 2026 and adding 30 days gives 10 September 2026, rolling cleanly past the end of August.

Example: add 3 months to 31 January

Because February has no 31st, the result snaps to 28 February (or 29 in a leap year) — the calendar-aware behaviour you would expect.

Example: subtract 90 days from a deadline

Take a project deadline of 1 December 2026 and subtract 90 days. The tool returns about 2 September 2026, a useful start date when you want a full quarter of working time before the deadline.

Example: add 2 weeks to a Monday

Adding 2 weeks to a Monday such as 3 August 2026 gives 17 August 2026, another Monday, because two weeks is exactly fourteen days and the weekday is preserved.

FAQ

How do I add weeks to a date?

Choose "add" and unit "weeks", then enter the number of weeks. The tool adds 7 days per week and handles month and year roll-overs automatically, so 3 weeks from late December can land in January.

What date is 30 days from today?

Enter today’s date, choose "add", unit "days", and type 30. The calculator returns the exact calendar date 30 midnights later, crossing month boundaries as needed.

What happens when I add months to a date?

Month arithmetic follows the calendar. Adding one month to a date near month-end lands on the last valid day of the target month (for example 31 January + 1 month becomes 28 or 29 February). This is the natural "one month later" result, not a fixed 30-day shift.

Related tools