Add or Subtract Days from a Date
Pick a start date, choose how much time to add or subtract, and read the resulting date and weekday immediately.
August 22, 2026
Saturday
30 days after Thursday, July 23, 2026 is Saturday, August 22, 2026.
Note: the result falls on a weekend.
Business-day mode skips Saturdays and Sundays; public holidays are not excluded.
How it works
- Set the start date — it defaults to today, and you can change it to any past or future date.
- Choose Add or Subtract, then enter the amount and pick days, weeks, months, or years.
- Read the resulting date with its weekday, or turn on business days only to skip Saturdays and Sundays.
Frequently asked questions
- How does the business days only option work?
- When the toggle is on, the calculator steps through the calendar one day at a time and only counts Monday through Friday, so Saturdays and Sundays are skipped entirely. Ten business days after a Friday therefore lands two full calendar weeks later. Public holidays are not skipped, because they differ by country and even by region.
- What happens when I add a month to January 31?
- The calculator clamps to the last real day of the target month, so January 31 plus one month gives February 28, or February 29 in a leap year. The same rule applies to adding years to February 29. This matches how spreadsheets and most legal deadline rules treat month arithmetic.
- Is the date I enter uploaded anywhere?
- No. The entire calculation runs in JavaScript inside your browser and no network request is made with your input. You can load the page, go offline, and the tool keeps working, which matters if the dates relate to contracts or medical schedules.
- What is this calculator typically used for?
- Common uses include finding a deadline 30, 60, or 90 days from an invoice date, working out a return-window cutoff, projecting a due date, or checking which weekday a date 6 weeks out falls on. The business-day mode fits shipping estimates and payroll or legal deadlines that only count working days.
- Can I subtract time to find a past date?
- Yes. Switch the control to Subtract and the calculator counts backwards using exactly the same rules, including weekend skipping in business-day mode. This is useful for questions like what date was 90 days ago or when a 14-day notice period must have started.
About this tool
This calculator answers a simple, constant question: what date is a certain number of days, weeks, months, or years before or after another date? Enter a start date — today is filled in for you — pick Add or Subtract, type an amount, and the result appears immediately with its weekday name and a plain-English sentence describing the calculation, so you can paste or read it without ambiguity.
Calendar arithmetic has traps that mental math misses. Months are 28 to 31 days long, so the tool adds months by moving the month number and clamping to the last valid day when needed: March 31 minus one month is February 28 or 29, never an invalid date. Leap years are handled the same way for year arithmetic. In business-day mode the calculator walks day by day and counts only Monday through Friday, the convention used for payment terms like net 30 business days, shipping estimates, and court or HR deadlines. Note that public holidays are not excluded, since they vary by jurisdiction.
Everything runs client-side in your browser. The dates you type are never sent to a server, stored, or logged, and the page keeps working offline once loaded. There is no account, no limit on calculations, and the result updates live on every keystroke rather than after a submit button.
A few practical tips: to find a date exactly N weekdays out, prefer the business-day toggle over multiplying weeks in your head, because the start weekday changes the answer. To check a notice period counted backwards, use Subtract with the deadline as the start date. And if a contract counts calendar days but you only care whether the deadline lands on a weekend, run it once in each mode and compare the two weekdays.