Add and subtract dates
Pick the date, the operation and the amount to see the final date and the weekday.
Free · no sign-up The values you type stay in your browser: nothing is sent or stored.
Final date
1/25/2026
- Weekday
- Sunday
Your result in words
Starting from 1/15/2026 and applying add of 10 days, you get to 1/25/2026 (Sunday).
Informational estimate, without fees or inflation. Check taxes and charges for your case; the real result may differ.
How it works
What it does
It adds or subtracts a number of days, weeks, months or years from a date. Useful for deadlines, due dates, pregnancy and warranty counts.
Cautions
It uses the real calendar, with leap years, but ignores holidays and business days; for that use the business days calculator.
Formula
How to calculate
D subscript f is the final date, subscript i the start date and n the amount. For months and years, a day that does not exist in the target falls on the last day of the month: Jan 31 plus 1 month gives Feb 28.
Example
With round numbers, so you can check the math:
Starting from 1/15/2026 and applying add of 10 days, you get to 1/25/2026 (Sunday).
Frequently asked questions
What if the day does not exist in the month?
The date falls on the last day of the target month.
Does the start day count?
No: the amount is added to the start date. Jan 15 plus 10 days is Jan 25.
Can I subtract?
Yes, choose "Subtract" as the operation.
Math checked by the JuntaTudo team · updated on Nov 12, 2026
