Add days to a date
Enter a start date and the days, weeks, months or years to add or subtract, and the new date appears with its weekday. 90 days after October 11, 2026 is Saturday, January 9, 2027.
Adding 90 days gives
SaturdayJanuary 9, 2027
- Calendar days apart
- 90
- Start date falls on
- Sunday
- ISO week of the result
- Week 1
- Day of the year
- 9 of 365
Order of the steps: years and months first, then weeks and days. If the month you land in is shorter (January 31 plus 1 month), the date moves to that month’s last day (February 28 or 29).
Dates after October 11, 2026
| Add | New date | Weekday |
|---|---|---|
| 30 days | November 10, 2026 | Tuesday |
| 60 days | December 10, 2026 | Thursday |
| 90 days | January 9, 2027 | Saturday |
| 100 days | January 19, 2027 | Tuesday |
| 180 days | April 9, 2027 | Friday |
| 365 days | October 11, 2027 | Monday |
| 1 month | November 11, 2026 | Wednesday |
| 6 months | April 11, 2027 | Sunday |
| 1 year | October 11, 2027 | Monday |
The table starts from October 11, 2026. Days are plain calendar days, so 90 days is exactly 90 steps on the calendar, while 3 months lands on the same day of the month three months later. The two can differ by a day or two, which is why a contract that says “3 months” and one that says “90 days” do not end on the same date.
The calculator keeps the order of the steps fixed and shows it under the fields: years and months first, then weeks and days.
What is the date 90 days from today?
Leave the start date on today, type 90 in the days box and read the date. As an example, 90 days after October 11, 2026 is Saturday, January 9, 2027. The table below lists other common offsets from that same day, so you can see how fast the calendar moves: 30, 60, 90, 100, 180 and 365 days.
How do you subtract days from a date?
Switch the control to Subtract and enter the days. Going back works the same way as going forward, across month and year ends: 45 days before October 11, 2026 is Thursday, August 27, 2026. You can mix units, for example 1 year and 2 weeks, and the tool applies months and years first and then the weeks and days.
What happens when you add a month to January 31?
February has no 31st, so the date moves to the last day of that month: January 31, 2026 plus 1 month is February 28, 2026, and January 31, 2028 plus 1 month is February 29, 2028, because 2028 has a 29th of February. The same rule applies to 29 February plus 1 year, which lands on 28 February in a common year. The rule is written under the fields so the result is never a surprise.
Is adding one month the same as adding 30 days?
No. Months have 28 to 31 days. January 15, 2026 plus 1 month is February 15, 2026, while January 15 plus 30 days is February 14, 2026. Use months when a deadline says "one month from" a date, and days when it says "30 days from". If a contract is unclear, ask which one it means.
Questions about add days
How do I add weeks to a date?
Type the number in the weeks box. A week is always 7 days, so 6 weeks is 42 days. You can combine weeks with days, months and years in one go.
How do I add business days instead of calendar days?
Use the business days calculator. It skips Saturdays and Sundays and, if you choose a list, the US federal or UK bank holidays for 2026 and 2027.
Can I add days across a leap year?
Yes. The calculator knows which years have a 29th of February, so 365 days after January 1, 2028 is December 31, 2028, not January 1, 2029.
What is the farthest date I can reach?
The calculator stops at the year 9999 and refuses results before the year 1. It says so instead of showing a wrong date.
Is the date I enter stored?
No. It stays in your browser. The start date and the amounts are copied into the page address only so that you can share the same calculation.
Related tools
Other ways to count with dates.
Business days
Working days between dates, or a date N working days away.Days between dates
Days, weeks, months and years from one date to another.Countdown timer
A live countdown to any date, with a link to share.Days until an event
Christmas, Thanksgiving, Easter and eight more.Week number
The ISO 8601 week of today or of any date.
Sources and limits
This page uses plain calendar arithmetic, so there is no outside source to cite. The method is described above, and the tests behind it were checked against independent calculations.
Not confirmed: The leap-year rule (divisible by 4, except century years not divisible by 400) is stated without an official source: we did not open one. The tests check it against .NET’s calendar.
This is a calculation aid. For payroll, contracts, court deadlines, visas or tax dates, confirm the count with the official calendar of the organisation that sets the deadline. Nothing you type leaves your browser.