Days Between Dates Calculator
Count the days between two dates — and the same gap in weeks, months and years — for deadlines, leases, pregnancies, projects and anniversaries.
Both dates are placed at midnight UTC and the difference in days is exact whole days.
How the days between dates calculator works
Both dates are placed at midnight UTC and the difference in days is exact whole days. The years-months-days breakdown counts full calendar months first (so 31 January to 28 February is one month), then the remaining days. Tick "include the end date" to count both ends, as leases and tickets often do.
Formula: days = (end − start) / 86,400,000 ms
Worked examples
| Inputs | Days | Note |
|---|---|---|
| 1 Jan → 31 Dec 2026 | 364 | 364 days (365 inclusive) |
| 2024-02-28 → 2024-03-01 | 2 | 2 days — 2024 is a leap year |
| 2026-03-15 → 2027-03-15 | 365 | 365 days |
FAQFrequently asked questions
Does the count include both dates?
By default no — it counts elapsed days (nights), like a hotel stay. Choose "inclusive" to count both ends.
Why is a month sometimes 28 days and sometimes 31?
The breakdown counts calendar months, whatever their length, then the leftover days.
Do leap years affect the count?
Yes — the day count is exact and includes 29 February when it falls in the span.
Does daylight saving change the result?
No; days are counted at UTC midnight, so clock changes never add or lose an hour.
How do I count working days?
The weekday row excludes Saturdays and Sundays; the working days calculator adds holidays you specify.
Where these figures come from
- ISO 8601 — Date and time — Representations for information interchange — the yyyy-mm-dd format and the week-numbering rules used here
- US Naval Observatory — Calendars — the Gregorian leap-year rule
- US Office of Personnel Management — federal holidays — federal holidays (not applied here)
Last checked: September 2026. The Gregorian calendar rules do not change; working-day counts exclude Saturdays and Sundays only.