Calculators
Add or Subtract Days Calculator
Add or subtract a number of days from any date to find the resulting date and the weekday it falls on.
About the Add or Subtract Days Calculator
The Add or Subtract Days Calculator finds the date a number of days, weeks, months or years before or after any date. Use quick buttons like +30 or +90 days, count working days only, and see the weekday, week number, day of the year and calendar days in between.
What you can do with the Add or Subtract Days Calculator
- Days to years: Add or subtract days, weeks, months or years.
- Quick buttons: +30, +90 days and more.
- Working days only: Skip weekends when counting.
- Date details: Weekday, week number and day of the year.
Days, weeks, months or years
Adding 90 days is not the same as adding 3 months, because months have different lengths. Pick the unit your rule uses: notice periods and return windows are often in days, subscriptions and rent in months.
Month-end dates
When the start day doesn't exist in the target month, like adding a month to 31 January, the result moves to the last day of that month, 28 or 29 February. That's how most banks and billing systems handle it.
Working days
For deadlines given in business days, switch on "Count working days only" and weekends are skipped. Public holidays aren't removed, add them on, or use the Working Days Calculator to count them.
Related tools
Frequently Asked Questions
What date is 90 days from today?
It's shown as soon as you open the tool, today + 90 days is the default.
How do I go back in time?
Tap "− Subtract" and enter the number of days, weeks, months or years.
Can it skip weekends?
Yes. Switch on "Count working days only" (with Days selected).
Is the start date counted when adding days?
No. Adding 1 day to a Monday gives Tuesday, so the start date is day 0. If you need to count the start date as day 1, for example in some deadlines, add one day less than the number you are given.
Is 90 days the same as 3 months?
Not always. From 1 November 2026, adding 90 days gives Saturday 30 January 2027, while adding 3 months gives 1 February 2027. Check whether your notice period, warranty or deadline is written in days or in months.
What happens when I add a year to 29 February?
The date moves to the last day of February when the new year is not a leap year. For example, 29 February 2024 plus 1 year gives 28 February 2025. The same rule applies when adding months to the 29th, 30th or 31st.
Does the working days option skip public holidays?
No. It skips only Saturdays and Sundays, so holidays such as Diwali, Independence Day or state holidays are still counted; add one extra working day for each holiday in the period. It also cannot treat Saturday as a working day.
Why is the working days switch ignored for weeks or months?
Working days are counted only when the unit is Days. With Weeks, Months or Years, the date moves on the calendar. To count working days, choose Days and enter the number, for example 10 for two working weeks.
How is the week number worked out?
It follows the ISO standard: weeks start on Monday, and week 1 is the week that contains the year's first Thursday. So early January dates can fall in week 52 or 53 of the previous year; 1 January 2027 is in week 53.
What if the result falls on a weekend?
The result line notes that it falls on a weekend. Many offices and banks move such deadlines to the next working day, so check the rule for your form, payment or court date and adjust the date if needed.
How do I find the last day of my notice period?
Enter your resignation date as the start date, choose Days or Months to match your contract, and add the notice period. For example, 60 days from 5 October 2026 is Friday 4 December 2026. Confirm with HR how your company counts the last day.
Read the guide
Related tools
- Markup Calculator, Add a markup percentage to a cost price to get the selling price, with the resulting profit and margin.
- Electricity Bill Calculator, Estimate what an appliance costs to run, from its wattage, hours of use and your electricity rate per unit.
- Running Pace Calculator, Enter a distance and your time to get your pace per kilometre and per mile, and your speed.
- Aspect Ratio Calculator, Find the simplified aspect ratio of any width and height, and the matching height for a new width.
- Hours Calculator, Work out how much time passed between a start and end time, in hours and minutes, including shifts that run past midnight.
- Percentage Calculator, Answer the everyday percentage questions at once: what % one number is of another, X% of a number, and adding or removing a percentage.
Quick Work Studio