Date Calculator
Days between two dates, with working days, or add days, weeks and months to a date.
Difference between two dates
Add or subtract from a date
Use a negative amount to go backwards.
About this tool
Two date jobs on one page. The difference side takes two dates and reports the exact day count, a friendly breakdown in years, months and days, whole weeks, and the number of working days in between. The other side answers "what date is 90 days from now": pick a date, an amount and a unit, and read off the result with its weekday.
The math runs on calendar dates, not clock times, so daylight saving changes never make a count off by one, and leap days are handled exactly. Adding months clamps sensibly: a month after January 31 is the last day of February. Handy for visa windows, notice periods, return deadlines and ages. Everything computes in your browser.
Frequently asked questions
- Is the end date included in the day count?
- The total counts the days you would cross moving from the first date to the second, so Monday to Friday of the same week is 4 days. Working days follow the same rule: the start day is not counted, the end day is.
- What happens when I add a month to January 31?
- You get the last day of February (the 28th, or 29th in a leap year). When the target month is shorter, the result clamps to its final day, which is the convention people expect for billing dates and deadlines.
- Does it handle leap years and daylight saving?
- Yes. February 29 is counted like any other day, and all math runs on calendar dates rather than clock times, so daylight saving changes can never make a count off by one.