Time & Date · Date Math
Add Working Days Calculator
Find the date that's a number of working (business) days before or after a date — skipping Saturdays and Sundays (or your own weekend) and any public or company holidays you add. Useful for delivery dates, SLAs, payment terms and project schedules.
A ready-made version of the Date Add/Subtract Calculator.
How this is calculated
Result = Start ± N units; months/years keep the day of the month, or use the last day if that month is shorter
- Working days
- Days that aren't weekend days or listed holidays; the start date itself isn't counted
- Day 1 option
- Counts the start date as the first day of the period (result one day earlier)
Adding days and weeks is plain counting. Months and years follow the calendar: 15 March + 1 month is 15 April, and when the target month is shorter the date moves to that month's last day — 31 January + 1 month is 28 or 29 February, not early March. Working days skip your weekend days and any holidays you list, which is how most deadlines and delivery estimates are counted.
Assumptions & sources
- Dates are calendar dates (no time of day or time zones).
- The start date isn't counted unless you turn on 'Count the start date as day 1'.
- Holidays only matter when they fall on working days.
- 1ISO 8601 — Date and time format (week numbering, calendar dates) — International Organization for Standardization
- 2Calendrical Calculations (Reingold & Dershowitz) — Cambridge University Press
Calculator ID TIME-DATEADD-001/workdays · version 2.0.0
Common questions
Is the start date counted?
No — counting starts the next working day, so 1 working day after a Friday is Monday. Turn on 'Count the start date as day 1' under More options if your rule counts it.
Can I use a different weekend?
Yes: Saturday–Sunday, Sunday only (common for six-day weeks), Friday–Saturday (Gulf countries), Friday only, or no weekend at all.
Which holidays should I add?
Only those that fall on working days and that your organisation or the relevant authority actually observes — national, state and company holidays differ.