Calculate duration between two dates, add or subtract days, months and years.
A date calculator lets you add or subtract days, weeks, months, or years from a specific date, or find the exact number of days between two dates. It's useful for project deadlines, contract terms, event planning, or just figuring out what day of the week a date 90 days from now falls on.
Counting days on a physical calendar is slow and easy to miscount, especially across month boundaries with different day counts. This tool exists to give an instant, accurate answer whether you're adding time to a date or measuring the gap between two of them.
For date differences, the calculator counts the exact number of calendar days between two dates, correctly handling leap years and different month lengths along the way. For adding or subtracting time, it applies the requested duration directly to the starting date — so 45 days from September 16, 2026 lands on October 31, 2026, a calculation that's easy to get wrong counting manually across a month boundary.
Enter both dates into the difference calculator mode, and it instantly counts the exact number of calendar days between them.
Yes, you can add or subtract days, weeks, months, or years, and the calculator adjusts the resulting date correctly for month length differences.
Yes, leap years are automatically factored into any date addition, subtraction, or difference calculation.
This tool calculates calendar days; for weekday-only counting, our Business Days Calculator is built specifically for that.
Yes, the calculated result includes the day of the week alongside the full date.