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Date Difference Calculator — Days Between Two Dates

Count the exact number of days between two dates, plus the gap broken down into years, months and days, in weeks, and the number of weekdays in between.

Runs entirely in your browser — nothing you enter is uploaded or stored.

Pick two dates to see the exact gap between them — in days, calendar units, weeks and weekdays.

What this calculator counts

Pick any two dates and you get the exact gap between them four ways: the total number of days, the same gap in calendar units (years, months and days), the gap in whole weeks, and how many of those days are weekdays versus weekend days. It handles leap years exactly and works for past dates, future dates and ranges spanning centuries.

Typical uses: days until a deadline or an event, the length of a notice period, the number of days between an invoice and its payment, how long you have held an investment, or the exact length of a project phase.

Counting the end date — or not

The single biggest source of off-by-one confusion in date counting is whether both endpoints count. By default this calculator measures from the start date to the end date, so Monday to Friday of the same week is 4 days — the way you would count nights in a hotel or the days an amount was outstanding. Tick “include the end date” and both endpoints count, making Monday to Friday 5 days — the way you would count billable days or days of leave taken.

A worked example: from 1 January 2026 to 15 March 2026 is 73 days (30 remaining days of January, 28 of February — 2026 is not a leap year — and 15 of March), which is 10 weeks and 3 days, or 2 months and 14 days in calendar units. Including the end date makes it 74.

Why “months” is not a fixed number of days

The calendar-units breakdown counts complete years first, then complete months, then leftover days — borrowing from the real length of the month before the end date when it needs to. Because months run from 28 to 31 days, “1 month” is a different number of days depending on where it falls; that is why two ranges can both be “3 months” yet differ by a couple of days in total. When precision matters — interest, deadlines, contracts — use the total-days figure, which is always exact.

Weekdays, weekends and working days

The weekday count covers Monday to Friday and is computed exactly, not estimated. It is not the same as “working days”: public holidays vary by country and region, so subtract the holidays that fall inside your range if you need business days. For a range that starts and ends on the same weekday, the split is easy to sanity-check — every full week contributes exactly 5 weekdays and 2 weekend days.

Frequently asked questions

Does the count include both dates?
By default no — the result is the number of days FROM the first date TO the second, so Monday to Friday of the same week is 4 days. Tick "include the end date" to count both endpoints (Monday to Friday becomes 5 days), which is how durations like hotel nights vs. billing days differ.
How is the years/months/days breakdown worked out?
In calendar units, the same way ages are counted: complete years first, then complete months, then leftover days — borrowing from the actual length of the month before the end date when needed. Because months differ in length, 1 month can mean 28 to 31 days; the total-days figure is always the exact one.
What counts as a weekday?
Monday to Friday. The weekday count excludes Saturdays and Sundays but knows nothing about public holidays, which vary by country — subtract any holidays in your range yourself if you need working days.
Are leap years handled correctly?
Yes. The calculation uses real calendar dates, so 29 February exists in leap years and the difference across any range — including century rules like 1900 vs 2000 — is exact.
Is anything I enter uploaded?
No. The dates never leave your browser — the arithmetic runs on your device and the page works offline once loaded.