How to Calculate Business Days Between Two Dates

A calendar day count between two dates is just subtraction: 22 August minus 1 August is 21 days. A business day count strips out every Saturday and Sunday (and, if you're being strict, public holidays), so the same range comes out closer to 15 working days. The gap grows the longer the range gets, which is why 'ships in 5 business days' and 'ships in 5 days' mean noticeably different things once a weekend sits in between.

Count the total calendar days between the start and end date. Divide by 7 to get the number of complete weeks, and multiply that by 5 — each full week contributes exactly 5 working days regardless of which day it starts on.

Take the remainder (the leftover days that don't make a full week) and check each one against a calendar: count it if it falls Monday through Friday, skip it if it's a Saturday or Sunday. Add that to the weekly total.

If either the start date or a specific public holiday needs to be excluded, subtract it once you've established whether it would otherwise have counted as a working day.

Whether the end date itself counts. 'From Monday to Friday' can mean 4 working days (exclusive of the end date) or 5 (inclusive) depending on convention — contracts and shipping estimates usually mean inclusive, so check which one applies before you commit to a number.

Which weekend days apply. Saturday and Sunday are standard in most of Europe and the Americas, but several Middle Eastern countries run a Friday–Saturday weekend instead. If you're calculating a deadline for an international team, this single setting can shift the answer by a full day.