Date & Time
Date Calculator
Add or subtract days, weeks, months, or years from any date. Use this add days to a date calculator to find what date is 90 days from today or any custom span.
Result
Resulting Date -
Day of Week -
ISO Format -
What date is it if I add 3 weeks, or subtract 14 days?
This is the general-purpose offset tool: start from any date, then add or subtract days, weeks, months, or years. Month math keeps the day number when it exists (Jan 31 + 1 month is not always Feb 31 — it clamps to the end of February).
Shortcuts like 90 days from today exist for the searches people type constantly. Come here when the offset is custom.
Days vs months
- Days are a fixed count. 30 days from Jan 31 is March 2 in a non-leap year — not “the end of February.”
- Months follow the calendar. Six months from Aug 31 lands on the last day of February, not a fictional Feb 31.
- Business deadlines that skip weekends belong on business days.
Frequently Asked Questions
How do I add days to a date using this calculator?
Pick a start date, select 'Add' as the operation, enter the number of days, choose 'Days' as the unit, then click Calculate Date. The result shows the new date along with its day of the week.
How do I subtract weeks from a date?
Select 'Subtract' as the operation, enter the number of weeks, choose 'Weeks' as the unit, and set your starting date. The calculator subtracts that many 7-day periods and shows the resulting date.
What date is 90 days from today?
Set the start date to today's date, choose 'Add', enter 90, select 'Days', and click Calculate. The tool will show the exact resulting date and its day of the week — useful for return windows, contract deadlines, or trial periods.
How does adding months to a date handle month-end overflow?
This calculator uses JavaScript's native date arithmetic, which rolls overflow into the next month. For example, adding 1 month to January 31 lands on March 2 or March 3 (depending on whether it's a leap year) rather than clamping to February 28/29, because February doesn't have a 31st day. Keep this in mind when adding months to dates near the end of a month.
Can I calculate a date in the past, not just the future?
Yes. Choose 'Subtract' instead of 'Add' to move backward from your start date by any number of days, weeks, months, or years.
Does this account for leap years when adding years?
Yes. If you add years to a February 29 leap-day date and land on a non-leap year, the date rolls forward to March 1, since February 29 doesn't exist in that year — this is standard date-arithmetic behavior.
What format is the result shown in?
The result is shown in a clear, unambiguous long format, such as 'Tuesday, March 4, 2025', along with the day of the week and an ISO-formatted (YYYY-MM-DD) version for easy copying.
Related Calculators
About these results: Figures are for planning only. Confirm anything you will buy, bill, or submit (materials, payroll, medical screening) against the label, a quote, or a professional.