Date Calculator
Date Calculator does the two date chores you reach for most: adding or subtracting a span of years, months, weeks and days from a date, and measuring the distance between two dates as a calendar breakdown plus totals.
It uses calendar-aware math, so month and year lengths are respected. Everything runs in your browser.
How to use Date Calculator
- 1
Pick a mode
Add / subtract to shift a date, or Difference to measure between two dates.
- 2
Enter the dates
Choose a start date and an amount, or pick the from and to dates.
- 3
Read the result
See the resulting date, or the gap as years/months/days plus total days and weeks.
Calendar-aware arithmetic
Adding a month is not the same as adding 30 days: months vary from 28 to 31 days, and years from 365 to 366. This calculator shifts by whole calendar units, so adding one month to 31 January lands on the right day, and adding a year respects leap years.
When you subtract, the same rules apply in reverse, which keeps anniversaries and due dates accurate.
Reading a date difference
The difference view gives a human breakdown — for example '2 years, 3 months, 5 days' — alongside the raw total number of days and an equivalent weeks-and-days figure. The calendar breakdown is best for ages and anniversaries; the totals are best for billing periods or deadlines.
The order of the two dates does not matter; the tool measures the gap either way.
Frequently asked questions
- Does it handle leap years and varying month lengths?
- Yes. Arithmetic is calendar-aware, so leap years and 28-to-31-day months are accounted for automatically.
- Can I subtract time from a date?
- Yes. Switch to Subtract and enter the years, months, weeks or days to go backwards.
- Are my dates uploaded?
- No. All calculations run locally in your browser.
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