Date Math Calculator
What date is 90 days from today? How long ago was March 3rd? Add and subtract time from a date, or measure the exact gap between two dates.
Dates
Pick a valid date.
Result
How to use the Date Math Calculator
- 1
Choose Add/Subtract or Between dates.
- 2
Enter your date(s) and amounts.
- 3
Read the result and weekday.
Helpful examples
- 90 days after a contract start date
- 6 months before a passport expiry
- Exact age in years, months and days between two dates
Month math done right
Adding one month to January 31 gives February 28 (or 29 in a leap year), the same rule banks and calendars use, rather than spilling into March.
Time between dates
The difference is shown both as a calendar breakdown (years, months, days) and as totals in days and weeks, so you can use whichever your form asks for.
Frequently asked questions
Does it account for leap years?
Yes, all calculations use the real calendar including leap years.
Is the end date included?
Between-dates totals exclude the start day by default. Turn on 'Include end date' to count both.
Can I count only business days?
Use the Days Left + Working Days Calculator for weekdays and holidays.