FREE WEB TOOL

Date difference calculator

Calculate the difference between two dates in days and weeks.

Use tool

Start dateEnd date

How to use this tool

Calculate the difference between two dates in days and weeks.

Set Start date, End date.
Use Calculate to process the input.
Compare the result with your source data and return to the input to make corrections.

Input and settings example

2026-09-01 → 2026-09-08: a difference of 7 days, or 1 week.

This differs from an inclusive count that counts both the start and end dates.

What to know before using it

Sep 1 to Sep 2 is normally a one-day difference, but counting both calendar dates gives two days. Contracts, stays and elapsed time use different conventions.

Common failure points

Date-only differences are not the same as elapsed hours.
Use a business-day tool when weekends and holidays matter.
Months and years do not map cleanly to a fixed number of days.

Practical example

Sep 1 to Sep 30 has an elapsed difference of 29 days, while “all days in September” is an inclusive 30-day count.