Date Difference Calculator

One span, several honest answers

How long is it between two dates? The question has more than one correct answer, and which one you want depends on why you are asking. A landlord wants months. A project manager wants working days. A contract wants a plain count of days. This calculator gives all of them at once for any two dates: total days, whole weeks plus a remainder, whole months, the years-months-days breakdown, and the number of working days in between.

Typical uses are notice periods, tenancy and contract lengths, project durations, visa and residency day counts, and settling the perennial argument about how long ago something happened.

A worked example: 1 January to 25 December 2026

From 1 January 2026 to 25 December 2026 is 358 days. Expressed as weeks that is 51 weeks and 1 day. Expressed as calendar units it is 0 years, 11 months and 24 days, and 11 whole months have elapsed. Of those 358 days, 256 are working days once Saturdays and Sundays are removed.

The five different-looking numbers describe the same span. 358 days is not "about 12 months" — it is 24 days short of a year, which is exactly the kind of gap that matters when a notice period or a lease is being counted.

Reversing the dates gives the same magnitude with a note that the second date is earlier. The tool does not silently return a negative, because a negative number of days is rarely what anyone wanted to see.

How each figure is derived

Total days is the plain difference between the two dates in UTC, divided by 24 hours and rounded. Working in UTC matters: a local-time date crossing a daylight-saving boundary makes a whole day 23 or 25 hours long, which is enough to shift a rounded day count by one at exactly the wrong moment.

Weeks are total days divided by seven, floored, with the remainder shown separately. The calendar breakdown counts the largest whole number of months that does not overshoot — clamping the day to the length of the destination month, so 31 January plus one month is 28 February — and then measures the leftover days from there. Working days exclude Saturdays and Sundays, counting the end date and not the start.

What is counted, and what is not deducted

Both ends are treated as whole calendar days with no time of day, so the count does not change during the day and does not depend on your time zone. The start date is excluded and the end date included, which is the convention used for commercial and delivery terms.

The working-day figure excludes weekends only. Public holidays are not deducted, because they vary by country, state and year and any built-in list would be quietly wrong; the dedicated business days calculator on this site lets you subtract them and lets you pick a different weekend. Note also that "whole months" and "total days" cannot be reconciled by a fixed multiplier — a month is anywhere from 28 to 31 days, so dividing days by 30 will not reproduce the month figure.