Add or subtract days — due date calculator
Find a date 7, 30 or 90 days ahead, or count backwards. Choose calendar days or a custom workweek and days off.
How it works
Positive amounts move forward and negative amounts move back, excluding the starting date. Working-day mode skips non-working weekdays and dates you enter. Zero always returns the starting date, even if it is not a workday.
Example
Monday 12 April 2027 plus 1 working day is Wednesday 14 April when the workweek is Monday–Friday and only 13 April is explicitly excluded.
Are Thai public holidays automatically included?
This tool has no automatic holiday list. Enter all applicable days off and substitute holidays yourself. The calendar shows separately reviewed holiday data and its coverage. A specific organization may apply different deadline rules.