Business Day Calculator
Business day calculator works out Working days and Calendar days from What to work out, Start date and End date. The default figures on this page give working days of 21 days; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
5 steps
- Weekend: Saturday and Sunday (5 working day(s) a week).
- Holiday calendar: US federal holidays (5 U.S.C. 6103).
- 2024-01-01 to 2024-01-31 inclusive is 31 calendar day(s).
- Remove 8 weekend day(s): 31 - 8 = 23 weekday(s).
- Remove 2 holiday(s) that fall on a working weekday: 23 - 2 = 21.
Holidays in the spantable
Its 7 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
5 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the business day calculator calculates
Counts working days between two dates, adds or subtracts a number of working days from a date, and rolls a deadline forward to the next working day under the Rule 6(a) convention.
How to use this business day calculator
Enter What to work out, Start date, End date and Working days to add. Working days updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Working days, Calendar days and Weekend days in the span.
The method follows Microsoft Excel NETWORKDAYS.INTL function specification, Microsoft Excel WORKDAY.INTL function specification, Federal Rules of Civil Procedure, Rule 6(a) and 6(d), 5 U.S.C. 6103 - Federal legal public holidays and 34 CFR 300.301(c)(1)(i) - Initial evaluations under the Individuals with Disabilities Education ACT.
January 2024 working days, US federal holidays example
With What to work out: count, Start date: 2024-01-01, End date: 2024-01-31, Holiday calendar: us-federal, the calculator returns Working days: 21, Calendar days: 31, Weekend days in the span: 8. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Working days, Calendar days and Weekend days in the span. The inputs you can vary are What to work out, Start date, End date, Working days to add, Deadline period and Deadline period unit.
Understanding Working days, Calendar days and Weekend days in the span
Holiday calendars differ by employer, court and country. Confirm the applicable holiday list and, for a legal deadline, the governing rule before relying on this date.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How do you calculate business days?
Counts working days between two dates, adds or subtracts a number of working days from a date, and rolls a deadline forward to the next working day under the Rule 6(a) convention. Open “How this is worked out” beside the result to see each step for your own figures.
Is 3 business days just 3 days?
Counts working days between two dates, adds or subtracts a number of working days from a date, and rolls a deadline forward to the next working day under the Rule 6(a) convention. Put your own figures in above and the working updates beside the result. For scale, the default figures on this page give 21 days.
Does 7 days mean 7 business days?
It needs What to work out, Start date, End date, Working days to add, Deadline period and Deadline period unit. Nothing else is required, and the figures stay in your browser.
Is 1 business day 5 days?
The result gives Working days, Calendar days, Weekend days in the span, Holidays excluded, Holidays in the span and Result date, each labelled with its unit so the figure can be read on its own.
What information do I need for the business day calculator?
You need What to work out, Start date, End date, Working days to add, Deadline period, Deadline period unit, Deadline counts and The period runs. The page opens with default figures that give working days of 21 days, so you can see the scale before entering your own.
What does this business day calculator show?
It shows Working days, Calendar days, Weekend days in the span, Holidays excluded, Holidays in the span, Result date, Result date falls on and Date before any roll-forward, with the working and any warnings for your entries.