Due dates
Add 15, 30 or 45 days to an invoice date to set the payment due date.
Add or Subtract Days
Start from any date and add or subtract days, weeks, months or years.
Your files stay with you. Your files never leave your browser. This tool runs on your device: nothing is uploaded to our servers, so there is nothing for us to store or see.
How to use it
- Pick the start date and Add or Subtract.
- Enter the years, months, weeks and days.
- Read the resulting date and the day of the week.
Where it helps
Deadlines
Work out the last day of a notice period, warranty or return window.
Looking back
Subtract days to find when a 90-day period started.
Good to know
Stays in your browser
Numbers you type are worked out on your device and never sent to our servers.
Holidays aren't skipped
Push the date on if a public holiday falls in the period.
Month ends
31 January plus a month lands on the last day of February.
Questions people ask
How do you find the date a number of days, weeks or months from now?
Pick a start date, choose Add or Subtract and enter any mix of years, months, weeks and days. The resulting date shows with its weekday. Tick the working-days box to count the weeks and days on Monday to Friday only. Public holidays aren't skipped, so move the date on yourself if one falls in between.
- + or - Any direction. Forward or back.
- Y M W D Mix the units. All at once.
- Mon-Fri Working days. Optional.
- Weekday Shown with date. Plan around weekends.
What happens when I add a month to the 31st?
If the next month is shorter, the date moves back to that month's last day. 31 January plus one month is 29 February in a leap year and 28 February otherwise. That matches how most banks and contracts treat month-end dates, so your due dates won't jump into the following month.
Can I count only working days?
Yes. Tick 'Count only working days' and the weeks and days are counted on Monday to Friday only. Years and months still move by the calendar. Public holidays aren't skipped, so if one falls inside the period, move the result on by one working day for each holiday.
Can I use it for an invoice due date?
Yes. Set the invoice date as the start, choose Add and enter 15, 30 or 45 days, whatever your payment terms say. The result is the due date and its weekday. If it lands on a Sunday, many businesses treat the next working day as the due date.
How do I work out the last day of a notice period?
Start from the day you resigned and add the notice period in days or months, as your contract states. Check whether your company counts the resignation day itself. If it does, subtract one day from the result to get your actual last working day. Your HR team can confirm the exact rule.
How do I find a date in the past?
Choose Subtract and enter how far back to go. For example, today minus 90 days tells you when a 90-day window started, which is useful for return policies, insurance waiting periods or bank statement requests. The weekday shown helps you match it to a calendar.
Can I add years, months and days together?
Yes. Fill in any mix of years, months, weeks and days, and the tool applies them all in one go. Years and months go first, then weeks and days. So 1 year, 2 months and 10 days from 5 January 2026 is 15 March 2027, shown with its weekday.
Why does the result show the date as yyyy-mm-dd too?
The yyyy-mm-dd form, such as 2026-11-17, is the international standard. It sorts correctly in spreadsheets and is what many government portals and software forms ask for. You can copy it straight in without retyping or worrying about the day and month swapping. The weekday and the everyday format sit right above it.
Can I use it for pregnancy or medicine schedules?
It can add weeks to a date, such as 40 weeks from the first day of the last period, which gives a rough due date. Medicine schedules work the same way. Always follow your doctor's dates, because they may adjust for scans and other details.
How do I find the date 100 days from today?
Leave the start date as today, choose Add and type 100 in the Days box. The result appears with its weekday. People use this for 100-day plans, challenges and visa or warranty rules, which often run for a fixed number of days rather than months.
Does it handle leap years?
Yes. The calendar is built into the calculation, so 29 February is counted whenever it falls in the period. Adding one year to 29 February 2028 gives 28 February 2029, because the next year has no 29 February. The weekday shown is always correct. You never need to check a calendar by hand.
What is the largest number I can add?
Use whole numbers of zero or more in each box. You can go many years forward or back, but if the result falls outside the range a browser can handle, the tool says the date is out of range. For everyday planning you'll never come near that limit.
Is the date counted in my time zone?
Yes. The tool uses plain calendar dates, so there's no time of day to shift between zones. If you need to know what time a deadline falls in another country, use the time zone converter as well, because midnight in India is still the previous day in the US.
Is anything I enter stored?
No. Everything is worked out in your browser and nothing reaches our servers. The page saves nothing after you close it and there's no sign-up. You can plan contract dates, legal deadlines or personal schedules without the details leaving your device. Close the tab and every date you typed is gone.
Does it work on a phone?
Yes. The start date opens your phone's calendar picker and the number boxes bring up the keypad. The resulting date and weekday appear immediately. It works in any mobile browser, so you can check a due date during a call with a customer. No app is needed at all.
Is the add or subtract days tool free?
Yes, it's free with no sign-up and no limit. It sits with the date difference and age calculators among the free tools from Marketiism. Businesses on Marketiism can set invoice due dates and send WhatsApp payment reminders automatically. Use it as often as you like, for work or personal plans.
Want this inside your own account?
Marketiism keeps your invoice numbers, GST reports, UPI payment links and WhatsApp reminders in one place. Leave your details and we'll call to set it up for your business, or start the trial yourself.
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