How to Count Business Days Correctly
Last updated 2026-06-05
“Your refund will arrive in 5 business days.” “Allow 7–10 business days for delivery.” “You have 3 business days to respond.” Business days run quietly underneath shipping, banking, contracts, and customer service — and they are counted differently from ordinary calendar days. Get the convention wrong and you will be a day or two off on something that matters.
This guide explains what a business day is, how to count business days from a date, and the edge cases that cause most mistakes.
What is a business day?
A business day (also called a working day) is a day on which most businesses and banks operate. In the United States and most of the English-speaking world, that means Monday through Friday. Saturdays and Sundays are not business days.
There are two common levels of strictness:
- Weekends only: count Monday–Friday, skip Saturday and Sunday. This is the everyday meaning.
- Weekends and public holidays: also skip recognized public holidays (such as federal holidays in the U.S.). Banks, courts, and shipping carriers typically use this stricter version.
tilwhen’s business-day figures use the weekends-only rule and label the result clearly. If your context observes public holidays, subtract those as well.
How to count business days
The counting itself is exclusive: the start day is day 0, and you count forward over working days only.
Suppose today is a Monday and you need to know the date 5 business days from now.
| Step | Day | Business day count |
|---|---|---|
| Start | Monday (today) | 0 |
| +1 | Tuesday | 1 |
| +1 | Wednesday | 2 |
| +1 | Thursday | 3 |
| +1 | Friday | 4 |
| skip | Saturday | — |
| skip | Sunday | — |
| +1 | next Monday | 5 |
So 5 business days from a Monday is the following Monday — seven calendar days later, because a full weekend falls in between. This is why “5 business days” so often means “about a week.”
Calendar days vs business days
The gap between the two grows as the count gets larger, because every seven calendar days contains only five business days.
| Business days | Approx. calendar days |
|---|---|
| 5 | 7 |
| 10 | 14 |
| 15 | 21 |
| 20 | 28 (about a month) |
A handy estimate: calendar days ≈ business days × 1.4 (plus a bit more if holidays fall in the window). For exact dates, count them out rather than estimating — the start weekday changes the result.
Where business-day math goes wrong
- Counting the start day. “3 business days from Monday” is Thursday, not Wednesday — today is day 0. Counting inclusively makes you a day early.
- Forgetting which day you start on. Five business days from a Thursday lands on the next Thursday, but it crosses a weekend differently than five from a Monday. The starting weekday always matters.
- Ignoring public holidays. If your bank or carrier skips holidays and you only skipped weekends, your estimate will be early during holiday-heavy months like November and December.
- Mixing the two with calendar deadlines. A contract that says “10 business days” is materially longer than “10 days.” Read the wording carefully.
A note on time zones
Business-day counting is about which calendar day it is, not the time of day, so it should be computed in the relevant local time zone. A cutoff like “orders placed by 5pm ship the same business day” depends on the seller’s local clock, not yours. When in doubt, assume the business’s time zone for cutoffs and your own for the resulting calendar dates. (More on this in date math across time zones.)
How tilwhen counts business days
Every relevant tilwhen page shows a business-day figure alongside the calendar-day answer:
- Monday–Friday only, weekends skipped.
- Exclusive counting (today is day 0), matching the everyday meaning of “X business days from today.”
- Public holidays are not excluded in this version, and the figure is labeled as such — so you can subtract any holidays your situation observes.
You will see it on pages like what date is 10 days from today and on every holiday countdown, where the business-day line sits just beneath the calendar-day answer.
Frequently asked questions
Does “business day” include Saturday? No. Business days are Monday through Friday. Saturday and Sunday are excluded.
Is the first day counted as a business day? No — counting is exclusive. Today is day 0, so “1 business day from today” is the next working day.
How many calendar days is 10 business days? Usually 14 (two work weeks), assuming no public holidays fall in the window. The exact dates depend on which weekday you start from.
Do business days skip holidays? It depends on the context. Banks, courts, and carriers usually skip public holidays; informal usage often only skips weekends. tilwhen skips weekends and labels the result so you can adjust.
Try it: see what date is 20 days from today for the business-day line, or read inclusive vs exclusive day counting.