Add or Subtract Days Calculator: Calendar and Working Days
Add or Subtract Days Calculator
Step forward or back from a date by calendar days or by working days, with the same holiday calendars as the working days tool. Built for notice periods, response deadlines and milestone dates.
Working day counting skips weekends and the selected holidays in whichever direction you step, and observed dates are used for weekend holidays. A 10 working day notice from a Friday therefore lands two full weeks later, not ten calendar days later, which is precisely the trap this tool exists to avoid.
How to use this tool
Start date, direction, a number, and whether those are calendar days or working days. The answer is a dated day of the week, and for working day counts the tool also states the calendar span it ended up covering, because ten working days from a Friday is fourteen calendar days and that gap is the entire reason to use the tool.
Deadlines count differently depending on their words
Within 10 days, within 10 business days, and within 10 working days of receipt are three different dates, and the difference is not pedantry: notice periods, response windows and cure periods in contracts run on exactly these words. Calendar days include weekends and holidays; working days skip both, using whichever holiday calendar governs. This tool applies the same computed Canadian and US federal calendars as the working days counter, with observed dates for weekend holidays.
Counting runs in either direction, because deadlines sometimes anchor backwards: submittals due 5 working days before a meeting are found by subtracting, and the tool steps over weekends and holidays on the way back just as it does forward.
A worked check you can repeat on paper
Add 10 working days to Friday, Aug 7, 2026, with no holidays in the way: the next working day is Monday the 10th, five working days land on Friday the 14th, and ten land on Friday, Aug 21. Fourteen calendar days for ten working ones. Now put a holiday in the path: two working days from Tuesday, Jun 30, 2026 on the Canadian calendar skips Canada Day on the Wednesday, giving Friday, Jul 3, not Thursday the 2nd.
Mistakes that catch people out
Counting the start day as day one. Day counting begins the day after the trigger in almost every legal and contractual convention. Fix: the tool starts stepping from the day after; if your document genuinely counts the trigger day, subtract one from N.
Mixing the day types mid-calculation. Ten working days is not two weeks when a holiday intervenes. Fix: pick the mode that matches the words and let the tool state the calendar span.
Landing on a non-working day and stopping there. A calendar-day deadline can land on a Sunday; many instruments roll it to the next working day, many do not. Fix: the tool reports the day of week precisely so the rollover question gets asked while it still matters.
How this was checked
Forward and backward stepping were verified against hand-traced cases: one working day forward from a Friday landing Monday, one back from a Monday landing Friday, ten forward from Friday Aug 7, 2026 landing Friday Aug 21, and the Canada Day case above. The holiday calendars are the same verified engine as the working days counter, including the Easter computation and observed-date shifts.
Related Calculators and Reference
For the quick version of this question, the Days From Today Calculator answers what date it will be a set number of days, weeks or months from today, with a link you can bookmark for any interval.
Measuring between two known dates instead of stepping from one is the Date Difference Calculator and, for business days, the Working Days Calculator. The most schedule-critical fixed offsets on a concrete job, 7, 28 and 56 days from the pour, have their own purpose-built Concrete Test Age Calculator.