Time and Date Difference Calculator
The exact gap between two dates and times — in days, hours, minutes and every other unit at once.
The difference is computed in milliseconds and converted.
How the time and date difference calculator works
The difference is computed in milliseconds and converted. Working in UTC avoids the daylight-saving trap: a day that "has 23 hours" locally still has 86,400,000 milliseconds of elapsed time, and mixing the two is where date arithmetic usually goes wrong.
The breakdown into years, months and days is separate arithmetic, because months are not a fixed length. That figure is calendar-based; the total-days figure is elapsed time.
Formula: difference = end − start, in milliseconds
Worked examples
| Inputs | Difference | Note |
|---|---|---|
| 1 Jan 09:00 to 1 Sep 17:30 | 243 days 8 h 30 min | 243 days 8 h 30 min |
| A single day | 1 days 0 h 0 min | exactly 1 day |
| Same moment | 0 days 0 h 0 min | zero |
FAQFrequently asked questions
How do I find the exact time between two dates?
Subtract the two moments. This page shows the result in every unit at once.
Why work in UTC?
Because local time has daylight-saving discontinuities. Elapsed time in UTC is unambiguous; a local "day" occasionally has 23 or 25 hours.
Why does the calendar breakdown differ from total days?
Because months vary in length. "Two months" is not a fixed number of days, so the two figures answer different questions.
Are the end dates inclusive?
The difference is exclusive — from one moment to another. Counting inclusive days means adding one.
Does the weekday count exclude holidays?
No, only weekends. Public holidays vary by jurisdiction and are not applied.
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.