Deadline Calculator
Find a deadline date — enter a start date and a number of days, choosing calendar days or business days (skipping weekends), to get the due date.
How to calculate a deadline
A deadline is just a start date plus a number of days. The catch is which days you count. In calendar-day mode the calculator counts every day, weekends included. In business-day mode it counts only Monday through Friday, skipping Saturdays and Sundays — the way many contracts, shipping windows and filing periods are measured. Enter the start date and the number of days above to get the due date and its weekday.
It counts forward from the day after the start date, the usual convention for “X days from” a date — so 10 calendar days from the 1st lands on the 11th. Enter a negative number to count backwards from a known due date to find the latest start.
Calendar days vs. business days
| Mode | Counts | Typical use |
|---|---|---|
| Calendar days | Every day | Returns, notices, general deadlines |
| Business days | Mon–Fri only | Shipping, processing, many contracts |
Business-day mode skips weekends but not public holidays, so adjust for any that fall in the window. Need the gap between two dates, or someone’s age, instead? Use the chronological age calculator.
Frequently asked questions
How do I calculate a deadline?
Add the number of days to the start date. In calendar-day mode the calculator counts every day; in business-day mode it skips Saturdays and Sundays so only working days count. Enter your start date and the number of days above to get the due date instantly.
What are business days?
Business days are the working days of the week — Monday through Friday — excluding weekends. They are how many contracts, shipping estimates and filing periods are counted. This calculator’s business-day mode skips weekends; it does not remove public holidays, so adjust for those.
Does the deadline calculator count the start date?
No — it counts forward from the day after the start date, which is the usual convention for “X days from” a date. So 10 days from the 1st lands on the 11th. Switch to business days to skip weekends in that count.