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Date Calculator

Count the days between two dates, or add or subtract days from a date. Results use the Gregorian calendar and whole-day arithmetic, so time zones and daylight saving never change the answer.

What do you want to calculate? Days between two dates Add or subtract days

First date Second date

Enter two dates.

Days, first to second (signed)-

Calendar difference (earlier to later)-

Weekday of first date-

Weekday of second date-

Dates are whole days on the proleptic Gregorian calendar, which is applied to every year from 1 to 9999. Dates must fall in that range. Everything runs in your browser; no dates are sent or stored.

How it works

Days between is the signed count of days from the first date to the second, so a second date earlier than the first gives a negative number.

Calendar difference is measured from the earlier date to the later one. Whole months are added to the earlier date, keeping its day of the month. If that day does not exist in the target month (for example the 31st in February), the last day of that month is used. The years and months are the most whole months that do not pass the later date, and the days are what remain. For example, 2020-01-31 to 2020-03-01 is 1 month and 1 day: 2020-01-31 plus 1 month is 2020-02-29, and 1 more day reaches 2020-03-01.

Add or subtract moves the date by that many whole days and shows the weekday of both dates.