Date / Time Calculator

Calculate the difference between two dates, or add/subtract days from a date.

Difference between two dates

From

Days—

Hours—

Minutes—

Total seconds—

Add or subtract from a date

Start date

Operation

Days

Hours

Minutes

Seconds

Result—

Features

Days between dates

Add/subtract days

Day of week

Days until date

How to Use

1. Pick two dates to see the days, weeks, and years between them.

2. Or pick a date and add/subtract days to find a new date.

About this tool

Date maths comes up constantly — how many days until a deadline, how long a project ran, what the date will be 90 days after signing — and it is easy to get wrong by hand because months and years vary in length. This calculator has two parts. The first measures the exact span between two date-times and shows it as days, hours, minutes and total seconds. The second takes a start date-time and adds or subtracts any number of days, hours, minutes and seconds to give the resulting date and time. Both use your device's calendar, so leap years are handled automatically. For legal or contractual deadlines, check whether the period counts calendar days or business days, since this tool counts every calendar day.

Frequently Asked Questions

Does the calculator count weekends and holidays?

Yes. It counts every calendar day, including weekends and public holidays. If a contract or visa rule counts only business days, subtract non-working days separately.

How are leap years handled?

The calculation uses real dates, so a span that includes 29 February is one day longer than the same span in a common year. Adding 365 days to 1 March 2027 lands on 29 February 2028, not 1 March.

Why is the difference in days shown with decimals?

The tool measures the exact time between two date-times. If the start is at 09:00 and the end is at 21:00 the next day, the difference is 1.5 days. Set both times to 00:00 to get whole days.

Is the first or last day included in the count?

The result is the elapsed time between the two moments, so from 1 June 00:00 to 2 June 00:00 is one day. If your rule counts both the first and the last day inclusively, add one day to the result.

Can daylight saving time affect the result?

Yes. Times are read in your device's local time zone, so a span that crosses a daylight saving change can be one hour shorter or longer than the whole number of days suggests.