Date difference calculator

Count the days between two calendar dates as end minus start, signed, in UTC. Example: 2025-01-01 to 2025-12-25 gives 358 days.

Result—

What to know

This mode takes a Start date and an End date and returns the number of whole days between them. The formula is days = (end - start) / 86,400,000 ms, rounded to a whole number, using midnight UTC for both dates.

The first date is not counted. From 2025-01-01 to 2025-12-25 the answer is 358 days, and from 2025-12-01 to 2025-12-25 it is 24. If your contract or school term counts both the first and the last day, add 1 to the shown number.

The result is signed. Putting an earlier End date than Start date yields a negative count such as -24, which is handy to see how long ago something happened without swapping the fields.

Leap days are handled by the calendar itself: 2024-01-01 to 2025-01-01 is 366 days. For gaps expressed in months or in years and months, use the month-difference or age pages, because a number of days does not convert cleanly into either.

Typical uses are project durations, notice periods, warranty windows and the gap between a signing date and a delivery date. For a trip from 2025-07-10 to 2025-07-14 the page shows 4, which matches 4 nights rather than 5 calendar days.

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How to use Date difference calculator
  1. Set Start date to 2025-01-01.
  2. Set End date to 2025-12-25.
  3. Read the Result line, which shows 358 days.
  4. Swap the two dates to see the same distance as -358 days.

Quick answers

How many days are there from 2024-02-28 to 2024-03-01?

2 days, because 2024 is a leap year and contains 29 February. In 2025 the same pair gives 1 day.

Can the answer be negative?

Yes. When End date is before Start date the sign flips, so you can tell at a glance that the second date lies in the past.

How do I count both the first and last day?

Take the displayed number and add 1. A hotel stay from the 10th to the 12th shows 2, which equals 2 nights and 3 calendar days.