Date Difference Calculator
Find the exact time between two dates in years, months and days plus total days and weeks — or add/subtract a number of days from any date. Great for deadlines, contracts and age.
About this tool
The Date Difference Calculator measures the exact span between two dates and breaks it down into years, months and days, plus a total number of days and weeks. It also works the other way, letting you add or subtract a number of days from any date.
It is built for deadlines, contract terms, project planning, age calculation and countdowns. Because date maths across months and leap years is error-prone by hand, the tool gives you a precise answer instantly.
How to use
- Pick the start date and the end date to measure the span between them.
- Read the difference broken down into years, months and days.
- Check the totals in days and weeks for a single overall figure.
- To add or subtract days, enter a base date and the number of days.
- Copy the resulting date or duration for your document or reminder.
Features
- Precise breakdown into years, months and days.
- Total-days and total-weeks figures for quick reference.
- Add or subtract any number of days from a chosen date.
- Correctly handles leap years and months of different lengths.
- Useful for deadlines, contracts, ages and countdowns.
- Instant recalculation whenever you change a date.
Frequently asked questions
Do my dates get uploaded anywhere?
No. The date arithmetic runs entirely in your browser, so the dates you enter are never sent to or stored on a server.
Does the calculator account for leap years?
Yes. It uses the browser's date engine, which correctly handles leap years and varying month lengths.
Are both the start and end dates counted?
The tool reports the number of full days between the two dates; if you need the range inclusive of both ends, add one day to the total.
Can I find a future date by adding days?
Yes. Enter a base date and a number of days to add, and the tool returns the resulting future date. Use a negative count to go back in time.
Can I use it to calculate someone's age?
Yes. Set the start date to a birth date and the end date to today, and the years/months/days breakdown gives an exact age.