Date Difference Calculator

Days between two dates

Enter two dates to see the span between them, or enter a start date and a number of days to find the end date.

Calculation Two dates Start date + days

From date

Include start & end dates as whole days

To date

Difference in days —

Difference in weeks —

Calendar breakdown —

Day count is whole calendar days between the dates (end minus start, or plus one at each end when Include start & end dates as whole days is checked). The same date with that option counts as one whole day — for example, arrival and departure on the same day. Weeks are days ÷ 7. The calendar breakdown counts whole years, months, and days from the earlier date to the later. In start date + days mode, day 1 is the start date when that option is checked (for example, 3 days from Monday counts Monday, Tuesday, and Wednesday).

How date difference calculations work

Calendar spans and day arithmetic

This tool counts days and weeks between two calendar dates, or adds a number of days to a start date to find an end date. It uses civil calendar dates rather than business-day calendars, so weekends and holidays still count unless you adjust manually.

Worked example

From 1 June to 15 June is 14 days (2 weeks) when both endpoints are handled the way the page documents. Adding 10 days to 20 February lands in early March — leap years change February’s length.

Common mistakes

Off-by-one errors when including or excluding the end date.
Expecting month lengths to be equal.
Mixing date difference with clock time zones — see Time Zones.

FAQs

Duration without dates?: Time Duration.

When this page helps

Use it when you want a transparent, browser-side calculation with the assumptions spelled out — then verify anything high-stakes against primary docs, a professional, or your own measurements. The related links below point to sibling tools and longer guides when you need more context.

Accuracy notes

Results depend entirely on the numbers you enter and the simplified model described above. Device clocks, tape measurements, market rates, and recipe conventions can all differ from a perfect textbook case. If an output looks surprising, re-check units first, then re-read the formula section.

Related: Time Duration, Time Zones.

Last updated: July 2026