Add or Subtract Days From a Date
90 days after Thursday, January 1, 2026 is Wednesday, April 1, 2026. Pick any start date, press Today for "from now", and add or subtract days, weeks, months, years or business days. Months and years land on the last day of the month when the day does not exist (January 31 + 1 month = February 28).
Updated Runs in your browser: nothing you enter is uploadedHow this tool works
Result
Wednesday, April 1, 2026
90 days after Thursday, January 1, 2026 is Wednesday, April 1, 2026.
- Date (ISO 8601)
- 2026-04-01
- Calendar days
- 90 days later (12 weeks, 6 days)
- Day of the year
- Day 91 of 2026
Common counts from Thursday, January 1, 2026
| Add | Date |
|---|---|
| 7 days (1 week) | Thursday, January 8, 2026 |
| 14 days (2 weeks) | Thursday, January 15, 2026 |
| 30 days | Saturday, January 31, 2026 |
| 60 days | Monday, March 2, 2026 |
| 90 days | Wednesday, April 1, 2026 |
| 120 days | Friday, May 1, 2026 |
| 180 days | Tuesday, June 30, 2026 |
| 365 days | Friday, January 1, 2027 |
| 10 business days | Thursday, January 15, 2026 |
| 10 business days, skipping US federal holidays | Thursday, January 15, 2026 |
| 6 months | Wednesday, July 1, 2026 |
| 1 year | Friday, January 1, 2027 |
Adding months at the end of a month
| Start | Change | Result |
|---|---|---|
| January 31, 2026 | + 1 month | Feb 28, 2026 |
| January 31, 2028 (leap year) | + 1 month | Feb 29, 2028 |
| March 31, 2026 | + 1 month | Apr 30, 2026 |
| March 31, 2026 | − 1 month | Feb 28, 2026 |
| August 31, 2026 | + 6 months | Feb 28, 2027 |
| February 29, 2028 | + 1 year | Feb 28, 2029 |
How long each unit is
| Unit | Length |
|---|---|
| Day | 1 calendar day (the clock time does not matter) |
| Week | 7 days |
| Month | 28 to 31 days: the same day number in the next month, or its last day |
| Year | 365 days, or 366 across a February 29; the same date next year, or February 28 |
| Business day | Monday to Friday; optionally not a US federal holiday |
| Business week | 5 business days, usually 7 calendar days |
How to add days to a date
- Pick the start date. Choose it in the date field, or press Today to count from today.
- Choose add or subtract. Subtract finds a date in the past, such as a deadline 30 days before an event.
- Enter the amount and the unit. Days, weeks, months, years or business days. For business days, choose whether US federal holidays are skipped too.
- Read the date. The result shows the weekday and date, the ISO date, how many calendar days away it is, and a note when a month end or a holiday changed it.
Frequently asked questions
- What date is 90 days from today?
- Press Today and keep 90 days: the result updates to your date. From January 1, 2026, for example, 90 days later is Wednesday, April 1, 2026. The start date is day 0, so the result is exactly 90 days after it.
- Does adding days count the start date?
- No. Adding 1 day to Monday gives Tuesday. Business days work the same way: 1 business day after Friday is Monday, and the start date is never one of the days counted.
- What is January 31 plus one month?
- February 28, or February 29 in a leap year. February has no 31st, so the date moves back to the last day of the month rather than spilling into March. Spreadsheets (EDATE) and most programming languages do the same.
- What is February 29 plus one year?
- February 28 of the next year, by the same end-of-month rule. Four years later it is February 29 again. Some legal rules, for example for birthdays, use March 1 instead; check if that matters for you.
- How do I add business days?
- Choose "Business days" as the unit. Saturdays and Sundays are skipped, and with "Weekends and US federal holidays" the eleven federal holidays are skipped on the days they are observed. 10 business days is usually two calendar weeks, more if a holiday falls in between.
- How do I count back from a date?
- Choose Subtract. For example, subtracting 6 weeks from an event date gives the date to send invitations; subtracting 10 business days gives a deadline that allows two working weeks.
How it works
Dates are turned into day numbers (days since January 1, 1970) with integer Gregorian-calendar arithmetic, so time zones and daylight saving time never shift a result. Days and weeks add 1 and 7 per unit. Months change the month and keep the day number, moving back to the last day of the month when that day does not exist; a year is 12 months. Business days skip Saturdays and Sundays in closed form, then step past each US federal holiday (5 U.S.C. § 6103, on its observed date, from 1971 on) until no holiday is crossed. Years 1 to 9999 are supported. Everything runs in your browser.
Sources
More free tools
- Days Between DatesCount the days between two dates, with weeks, months and years, business days and US federal holidays. Include or leave out the end date.
- Business Days CalculatorCount working days between two dates, or add and subtract business days from a date. Skips weekends and US federal holidays on their observed dates.
- Time CalculatorAdd hours and minutes to a date and time ("72 hours from now"), find the hours between two times, and add up a timesheet, with daylight saving handled.
- Day of the Week CalculatorFind out what day of the week any date falls on, from year 1 to 9999. Shows the ISO week, the nth weekday of the month, and a Doomsday-rule mental method.
- Week Number CalculatorFind the week number of any date in the ISO 8601 and US systems, or the dates a week number covers. Also day of the year, days left and quarter.
- Age CalculatorYour exact age in years, months and days on any date, in total weeks, days and hours, with a countdown to your next birthday. Feb 29 births handled.