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

Quick answer: 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

Thursday, June 18, 2026

Adding 30 days to 2026-05-19 gives 2026-06-18 (Thursday, June 18, 2026).

ISO Date

2026-06-18

Days Added/Subtracted

+30 days

How to Use This Date Add Calculator

1Enter your starting date.
2Enter the amount to add (positive) or subtract (negative).
3Select the unit: days, weeks, months, or years.
4Read 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.

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Date Add / Subtract Calculator

How to Use This Date Add Calculator

Frequently Asked Questions

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