Ten days is one week and three days. It is short enough that most people try to count it on their fingers, and just long enough that they get it wrong, because the answer depends entirely on whether the ten days are calendar days or business days.
Ten days from today lands three weekdays past today. Ten days from a Monday is a Thursday; ten days from a Friday is the Monday after next.
Ten days or ten business days?
This one distinction decides most ten-day questions, and the two readings are four days apart:
- 10 calendar days is always 10 days, containing 6, 7 or 8 weekdays depending on where in the week you start
- 10 business days is two full working weeks, which spans 12 to 14 calendar days
The weekday count inside a 10-day window is 8 if you start on a Sunday, Monday or Tuesday; 7 if you start on a Wednesday or Saturday; and 6 if you start on a Thursday or Friday. A ten-day window that begins on a Thursday gives you a third less working time than one that begins on a Monday.
If a document does not say business days or working days, calendar days is the default reading and the safer assumption. The error only runs one way: assume business days when the contract meant calendar days and you are late.
Where the 10-day window shows up
Ten days is the standard length for a short window that still needs to survive a weekend:
- Weather: the 10-day forecast is the usual outer limit of consumer forecasting, because model skill drops sharply past about a week
- Insurance: free-look periods, during which a new policy can be cancelled for a full refund, are commonly 10 days, though several states mandate longer
- Real estate: 10-day inspection and option periods appear in many residential purchase contracts
- Retail and shipping: 10-day price-match windows, and 10-day delivery estimates for standard ground service
- Notices: many state landlord-tenant statutes and agency notices use a 10-day period to respond or cure, though the figure varies widely by jurisdiction
Because 10 is not a multiple of seven, none of these land on the weekday you started from, which is why they get diarised wrong more often than a 7-day or 14-day window.
Frequently Asked Questions
How many weekdays are in 10 days?
Six, seven or eight, depending on the starting weekday. It is 8 from a Sunday, Monday or Tuesday, 7 from a Wednesday or Saturday, and 6 from a Thursday or Friday, assuming a Monday-to-Friday week and no public holiday.
Is 10 business days the same as 10 days?
No. Ten business days is two full working weeks, which spans 12 to 14 calendar days. Ten calendar days is 10 days containing only 6 to 8 weekdays. Treating them as the same is the most common ten-day counting error.
What weekday is 10 days from today?
Three weekdays past today. Ten days from a Monday is a Thursday, from a Wednesday is a Saturday, and from a Friday is a Monday. Since 10 is not a multiple of seven, it never lands on the same weekday you start from.
How many weeks is 10 days?
One week and three days, or about 1.43 weeks. It is the shortest span in common use that is neither a round week nor a round fortnight.