Date calculator
Calculator
The calculator needs JavaScript. The tables below give the same numbers for common cases.
How it is worked out
- Add or subtract the years and months first; if the day does not exist in the new month (for example the 31st), it moves to the last day of that month.
- Then add or subtract the days: Wednesday, December 23, 2026.
| Inputs | Answer |
|---|---|
| Start date: 2026-11-13; Operation: Add; Years: 0; Months: 1; Days: 10 | Friday, November 13, 2026 plus 0 years, 1 months and 10 days is Wednesday, December 23, 2026. |
| Start date: 2026-01-31; Operation: Add; Years: 0; Months: 1; Days: 0 | Saturday, January 31, 2026 plus 0 years, 1 months and 0 days is Saturday, February 28, 2026. |
| Start date: 2026-12-25; Operation: Subtract; Years: 0; Months: 0; Days: 100 | Friday, December 25, 2026 minus 0 years, 0 months and 100 days is Wednesday, September 16, 2026. |
How to use it
Years and months are added first; if the day does not exist in the new month (for example 31 January plus one month), it moves to the last day of that month (28 February in 2026). The days are then added or subtracted exactly.
Use it for deadlines, due dates, warranty ends and contract terms. The result shows the weekday and the day of the year.
Frequently asked questions
What is 31 January plus one month?
The last day of February: 28 February 2026 (29 in a leap year).
How do I find the date 90 days from today?
Enter today as the start date and add 90 days.
Does it count weekends?
Yes, all calendar days; use the business days calculator to skip weekends.
Method: standard arithmetic shown step by step; no outside data is used. Checked 2026-11-12.
About · How we verify this · Editorial policy · Corrections
General information only. Results are plain arithmetic on the numbers you enter; check anything important (money, health, school work) against your own records or the official source.