Add or subtract days from a date
Deadlines are usually expressed as a duration — 90 days from signature, 30 working days from filing, six months from today. This turns that into an actual date on the calendar.
How to use the add or subtract days from a date
- Pick your start date.
- Choose whether to add or subtract, and by how much.
- Select the unit, including working days if weekends do not count.
How it works
Day, week and year arithmetic is straightforward. Month arithmetic follows the usual convention: adding a month to 31 January lands on 28 February (or 29 in a leap year), because there is no 31st. Working-day mode steps forward or back one day at a time and skips Saturdays and Sundays.
The extra rows are there because official deadlines often need them — the ISO date for forms, the weekday to check it is not a closed day, and the week number for anyone working to a fiscal calendar.
Common questions
Does working-day mode skip holidays?
No, only weekends. Public holidays vary by country, so add them manually.
What does 'six months from today' actually mean?
The same date number six months on, adjusted back if that month is shorter. This tool follows that convention.