Datetime Calculator - Compute Differences and Add/Subtract Time

How to Use

1. In the Difference tab, enter start and end datetimes to automatically compute the gap
2. Results show a breakdown in years, months, days, hours, minutes, and seconds, plus totals
3. In the Add/Subtract tab, set a base datetime, operation, value, and unit
4. The result is computed automatically as you configure the options

Usage Examples

Days until a deadline:
Set today as start and the deadline as end to instantly see the remaining days.

Date 30 days from now:
Add 30 days to today's datetime to find the target date.

Employment duration:
Calculate years and months of employment from the hire date to today.

FAQ

How is "month" calculated?

365.25 days = 1 year and 30.44 days = 1 month are used as approximations. Minor inaccuracies may occur.

Can I specify seconds?

Yes. The datetime-local field accepts seconds.

Can I calculate past dates?

Yes. If the end datetime is before the start, the result is shown with a minus sign.

Is data sent to a server?

No. Everything runs in the browser.

Is timezone taken into account?

The browser's local timezone is used.

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