Add days to a date calculator
Choose a start date and how many days, weeks or months to add or subtract. The result shows the date and its weekday.
Runs in your browser · Gregorian calendarLast reviewed: October 9, 2026
The short answer
To add days to a date, count forward starting the day after the start date. For example, 60 days after November 1, 2026, is Thursday, December 31, 2026. If the start date itself counts as day 1, the period ends one day earlier, on Wednesday, December 30, 2026.
How it is calculated
Result = start date + months + weeks × 7 + days
Start date counted as day 1: result − 1 day
Subtracting runs the same steps backward
Worked example
Emily, a freelance designer in Ohio, sends an invoice on November 1, 2026, with payment due in 60 days. When is it due?
- Start: Sunday, November 1, 2026
- Add 60 days: 29 days to the end of November, 31 in December, 0 left over
- Result: Thursday, December 31, 2026
- If her terms counted November 1 as day 1, the due date would be Wednesday, December 30, 2026
The invoice is due on Thursday, December 31, 2026.
Quick reference table
| Period | Date |
|---|---|
| 7 days | Sunday, November 8, 2026 |
| 14 days | Sunday, November 15, 2026 |
| 30 days | Tuesday, December 1, 2026 |
| 45 days | Wednesday, December 16, 2026 |
| 60 days | Thursday, December 31, 2026 |
| 90 days | Saturday, January 30, 2027 |
| 120 days | Monday, March 1, 2027 |
| 180 days | Friday, April 30, 2027 |
| 365 days | Monday, November 1, 2027 |
| 6 months | Saturday, May 1, 2027 |
| 1 year (12 months) | Monday, November 1, 2027 |
Special cases and common mistakes
- Day 0 or day 1? This calculator, Excel (=A1+60) and most date tools count from the day after the start. Some agreements count the start day as day 1; check that option and the result moves one day earlier.
- Adding months is not adding 30 days. One month after January 31, 2027, is February 28, 2027, because February has no 31st. The calculator stops at the last day of the month, like Excel's EDATE.
- 365 days is not always a year. From November 1, 2027, 365 days lands on Tuesday, October 31, 2028, because February 2028 has 29 days, while 12 months lands on Wednesday, November 1, 2028. Use the period your agreement names.
- Weekends and holidays are included. Every calendar day counts here. If a deadline is in business days, use the working days calculator instead.
- Check the rule that sets your deadline. Courts, agencies and contracts have their own counting rules, for example for deadlines that land on a weekend. This tool only does the date arithmetic.
Frequently asked questions
What date is 90 days from today?
Press "Today," then the 90-day button. The calculator shows the date with its weekday. From November 1, 2026, 90 days later is Saturday, January 30, 2027.
How do I add days to a date?
Enter the start date and the number of days, then choose Add. You can also mix in weeks and months; months are applied first, then weeks and days.
How do I subtract days from a date?
Choose Subtract. It is useful for working back from a deadline, for example to find the date 30 days before a move-out day.
How do I add days to a date in Excel?
If the date is in A1, =A1+30 adds 30 days and =EDATE(A1,3) adds 3 months. Format the cell as a date to see the result.
What is 6 months from a date?
Add 6 in the Months field or press the 6-month button. From November 1, 2026, 6 months later is Saturday, May 1, 2027.