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Date & Timedates

Date Difference Calculator

Days between two dates, in calendar units and working days. Whether the end date counts is an input rather than a convention, because that single choice is behind most off-by-one disputes in notice periods and contracts.

Also called: days between dates, date calculator.

Working week
Days
358

358 days between the two dates, which is 0 years, 11 months and 24 days. 256 of those are working days on a five day week. The end date is not counted. A notice period may use the inclusive convention instead, which adds a day.

Working days
256
Non-working days
102
Whole weeks
51
Whole months
11
Hours
8,592
In years, months and days
0 years, 11 months and 24 days
Start falls on a
Thursday
End falls on a
Friday
On working days
256 of those are working days on a five day week.
On counting the end date
The end date is not counted. A notice period may use the inclusive convention instead, which adds a day.
How this is calculated
Method and background

How this is calculated

The difference in milliseconds over a day, computed at UTC midnight so a daylight saving boundary cannot produce a fraction. The inclusive question is the one worth surfacing: a thirty day notice period served on the first ends on the thirtieth or the thirty-first depending on the convention, and contracts differ. Working days exclude weekends on the pattern you choose, since a six day week is standard in much of the world, and subtract any holidays you enter.

exact because both ends sit at UTC midnight, so no daylight saving change can produce a fractional day
t
Timestamps

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

new year to christmas

From
2026-01-01
To
2026-12-25
Count the end date as a full day
No
Public holidays in the range
0
Working week
Monday to Friday

Days358

358 days across a non-leap year

Open this example

counting the end date adds one

From
2026-01-01
To
2026-12-25
Count the end date as a full day
Yes
Public holidays in the range
0
Working week
Monday to Friday

Days359

boundary: the convention behind most off-by-one disputes

Open this example

Method and limits

What it assumes

  • Both dates at UTC midnight, so time of day never affects the count.

What it deliberately does not model

  • Public holidays vary by country and region, so they are an input rather than a lookup.
  • A six day working week still treats Sunday as the rest day, which is not universal.

Formula version 1.0.0 · definition 1.0.0 · India · Report a problem with this calculator

Frequently asked questions

Should the end date count?
It depends on the contract. A thirty day period from the first ends on the thirtieth exclusive or the thirty-first inclusive, and both conventions are in use, which is why it is a choice here rather than an assumption.
Why compute at UTC midnight?
Because a range crossing a daylight saving boundary has a 23 or 25 hour day in it, and dividing elapsed milliseconds by a day then returns a fraction that rounds unpredictably.