How are end-of-month calculations handled?

For example, adding 1 month to January 31st results in February 28th (or 29th in leap years).

Are time zones considered?

Calculations are based on your browser's local time zone.

No. All processing happens in your browser.

Yes. Entering negative values lets you calculate dates in the past direction.

Yes. You can specify multiple units simultaneously to calculate the resulting date and time.

Calculate result datetime by adding or subtracting a duration. Supports years, months, days, hours, minutes and seconds. Free.

Base datetime

Operation Value Unit

How are end-of-month calculations handled?: For example, adding 1 month to January 31st results in February 28th (or 29th in leap years).
Are time zones considered?: Calculations are based on your browser's local time zone.
Is my data sent to a server?: No. All processing happens in your browser.
Can I use negative values for subtraction?: Yes. Entering negative values lets you calculate dates in the past direction.
Can I specify years, months, days, hours, minutes, and seconds at the same time?: Yes. You can specify multiple units simultaneously to calculate the resulting date and time.

Last Updated: 2026-02-21