Find the exact number of days, weeks, and years between two dates, or add and subtract days from any date.
Use the "Difference Between Dates" tab to find how much time separates two dates — in total days, weeks, and a full years/months/days breakdown. Switch to the "Add / Subtract Days" tab to find what date falls a certain number of days before or after a given date, along with the day of the week it lands on.
The difference in days between two dates is calculated by converting each date to a single timestamp and dividing the gap by the number of milliseconds in a day (86,400,000). The years/months/days breakdown accounts for varying month lengths and leap years by comparing calendar components directly rather than just dividing total days by 365.
If you calculate the difference between January 1, 2026 and July 19, 2026, the tool returns 199 total days, which breaks down to 28 weeks and 3 days, or 6 months and 18 days. For the Add/Subtract tab, adding 45 days to July 19, 2026 lands on September 2, 2026 — a Wednesday.
This kind of date math comes up when tracking project deadlines, calculating someone's exact age in years and months, figuring out contract or lease end dates, planning countdowns to an event, or working out a due date a fixed number of days from today.
Does it account for leap years? Yes — because the calculation works directly with real calendar dates rather than a fixed 365-day year, leap years (like 2028) are handled automatically.
Can I subtract days from a date to go backward? Yes — choose "Subtract" in the Add/Subtract tab to find a date that many days before your chosen start date.
It counts the exact number of days (and optionally breaks that down into years, months, and days) between your two chosen dates.
Yes, the day count is calendar-accurate and correctly includes leap years falling within the range.
Depending on the calculator's settings, you may be able to choose inclusive or exclusive counting, which changes the result by exactly one day.