Date Calculator

Find the number of days between two dates, add or subtract time from a date, or check what day of the week a date falls on.

Start date

End date

Include the end date in the count

Total duration

— days

—

Total days

—

Full weeks

—

Weekdays (Mon–Fri)

Start date

Add

Subtract

Amount

Unit

Resulting date

—

Date

Falls on a

—

Runs in your browserYour dates are never sent anywhere — everything calculates instantly on your device.

Accounts for leap yearsAll calculations use real calendar dates, so leap years and varying month lengths are handled correctly.

Free, no sign-upUse it for deadlines, trip planning, or contract terms — no limits.

How to use the Date Calculator

Pick a mode. Choose between finding the number of days between two dates, adding/subtracting time from a date, or finding the day of the week.

Enter your dates. Use the date pickers to select the start date (and end date, if applicable).

Adjust the amount. For add/subtract mode, enter the number of days, weeks, or months — use a negative number to subtract instead of add.

Read the result. The calculated date or day count updates instantly as you change any input.

All calculations happen locally in your browser and correctly account for leap years — nothing you enter is transmitted or stored.

Features

Leap-year accurate

Correctly handles leap years when counting or adding/subtracting across years.

Add or subtract

Use negative values to subtract days, weeks, or months instead of adding them.

Day-of-week lookup

Instantly find what day of the week any date falls on.

100% client-side

Nothing you enter is sent to a server or stored anywhere.

Frequently asked questions

Does this account for leap years?

Yes. The calculator correctly handles leap years when counting days between dates or adding/subtracting months and years.

Can I subtract days from a date instead of adding?

Yes. Enter a negative number of days, weeks, or months to subtract from the starting date instead of adding to it.

Is my date data sent anywhere?

No. All calculations happen locally in your browser. Nothing you enter is transmitted or stored.