What happens when adding months crosses a month boundary?

The calculator adds the calendar months directly. Adding 1 month to January 31 gives February 28/29 (last day of February), matching how most date tools handle this.

Does this account for leap years?

Yes — the JavaScript Date object handles leap year logic automatically.

Date Add / Subtract Calculator

Enter a date and an amount to add or subtract to find the resulting date.

Enter a starting date and choose how many days, weeks, months, or years to add or subtract. Instantly see the resulting date — useful for deadlines, countdowns, and contract dates.

Last reviewed: April 2026Report an error

Start Date

Amount (negative to subtract)

Unit

Result Date

Wednesday, May 20, 2026

Adding 30 days to 2026-04-20 gives 2026-05-20 (Wednesday, May 20, 2026).

ISO Date

2026-05-20

Days Added/Subtracted

+30 days

How to Use This Date Add Calculator

Enter your starting date.
Enter the amount to add (positive) or subtract (negative).
Select the unit: days, weeks, months, or years.
Read the resulting date.

Frequently Asked Questions

: The calculator adds the calendar months directly. Adding 1 month to January 31 gives February 28/29 (last day of February), matching how most date tools handle this.
: Yes — the JavaScript Date object handles leap year logic automatically.

</> Embed this calculator on your website

<iframe src="https://calqpro.com/calculators/date-add-subtract-calculator" width="100%" height="600" frameborder="0" title="Calqpro Calculator" loading="lazy"></iframe>
<p>Powered by <a href="https://calqpro.com">Calqpro</a></p>

Date Add / Subtract Calculator

How to Use This Date Add Calculator

Frequently Asked Questions

Related Calculators