4 min read · January 19, 2027
How to Calculate Business Days Between Two Dates
To estimate business days between two dates, take the total calendar days, multiply by 5/7 to remove weekends, then subtract any public holidays that fall in the range. A 14-day span has 10 business days if it contains exactly two weekends and no holidays.
The quick estimate
Total calendar days × 5/7 gives a fast estimate of business days, since 5 out of every 7 days are weekdays. A 14-day span (exactly two full weeks) is 14 × 5/7 = 10 business days — clean, because two full weeks contain exactly four weekend days and ten weekdays.
This estimate is exact whenever the range lines up on full weeks and there are no holidays inside it. It gets slightly approximate for ranges that start or end mid-week, since 5/7 is an average rate, not a day-by-day count — for those, exact counting (below) is more reliable.
Exact counting, day by day
For precision, walk each calendar day in the range and count only Monday through Friday, skipping Saturday and Sunday entirely. This is what dedicated business-day calculators automate, and it's the only approach that's exact for ranges that don't land on clean week boundaries.
Get the total calendar days from a date-difference tool first (14, in the example above), then either apply the 5/7 estimate for a fast answer or count weekdays individually against a calendar for an exact one — the calendar-day total is the necessary starting input either way.
Don't forget public holidays
Neither the 5/7 estimate nor a plain weekday count knows about holidays — New Year's Day, national holidays, and any company-specific closures all need to be subtracted separately once you know how many fall inside your date range. A 10-business-day estimate that includes a Monday holiday is really 9 working days.
This is exactly why deadline-sensitive business days (contract terms, shipping estimates, legal notice periods) are usually specified with an explicit holiday calendar attached, rather than left to a generic 5/7 rule that can't account for a specific year's holiday schedule.
Put it into practice
The fastest way to learn the math is to play with the numbers.
Open the Date Difference Calculator