Work out due date from start date instantly with clear inputs, formula shown and shareable results.
Twenty working days from 1 April 2026 is 29 April - 28 calendar days, because four weekends intervene. Contracts that specify working days therefore run about 40% longer in calendar terms than the number suggests, which is why the day type must always be stated explicitly.
Working day due date
add days one at a time, skipping Saturdays and Sundays
Calendar due date
due = start + days
It varies, and the difference is material - 20 working days is 28 calendar days. Always check whether the contract says business days or just days.
Here counting begins the day after the start date, which is the usual convention for notice and turnaround periods.