Add or Subtract Days
Add or subtract days, weeks, months or years from any date and instantly see the resulting date. Free and private — all math happens in your browser.
How to add or subtract days from a date
- Pick a start date. It defaults to today, so you can immediately answer questions like “what date is 30 days from now?”. Change it to any other date if needed.
- Choose add or subtract and enter an amount. Switch between + Add and − Subtract, type a number, and pick days, weeks, months or years as the unit.
- Read the result. The resulting date appears instantly with its weekday, ISO format (YYYY-MM-DD) and how far it is from today. Copy it with one click.
About this tool
This free date calculator moves any calendar date forward or backward by an exact number of days, weeks, months or years. Typical uses: finding a deadline that is 90 days after a contract is signed, working out when a 6-week notice period ends, checking what date it was 100 days ago, computing warranty or visa expiry dates, and planning medication or billing cycles. The math is fully calendar-aware — leap years and different month lengths are handled correctly, with no off-by-one surprises.
Everything runs locally in your browser, so the dates you enter are never uploaded or stored. If you need to skip weekends instead of counting every calendar day, try the Working Days Calculator.
Frequently asked questions
What happens if I add 1 month to January 31?
When the target month is shorter, the day is clamped to the last day of that month: January 31 + 1 month gives February 28 (or February 29 in a leap year). The same rule applies when adding years to February 29. This matches how spreadsheets and most date libraries behave.
Are leap years taken into account?
Yes. The calculator uses the full Gregorian rules, so adding 365 days is not always the same as adding 1 year — across a leap day, one calendar year equals 366 days, and the tool gets this right automatically.
Can I go back in time or use negative results?
Yes — choose − Subtract to move backward. You can chain calculations by copying the ISO result into the start date field, and the “From today” stat shows whether the result lands in the past or the future.
Does the tool count business days?
No, it counts every calendar day, including weekends and holidays. For business-day math (Monday–Friday, with optional holidays), use the dedicated Working Days Calculator instead.