Quick answer
Count the actual weekdays in the specific month, then subtract your own holiday calendar. Never assume a standard month.
The variation is larger than people expect
A month with 28 days that starts on a Monday contains exactly 20 weekdays. A 31-day month starting on a Monday contains 23. Before any holidays are considered, that is a fifteen per cent swing in available capacity between two ordinary months.
Because the average is close to 21.7, a plan built on "about 22 working days" will be roughly right on average and materially wrong in specific months — always in the direction that is discovered late. February and months that start on a weekend are the usual culprits.
Use this guide with the right tool: Open the Working Days in Month Calculator for the number of weekdays in a selected calendar month. If the question shifts, compare it with the Business Days Calculator or the Working Hours Between Dates Calculator.
Holidays concentrate unevenly
Holidays are not spread evenly through the year. In most Western calendars, December and the spring months carry a disproportionate share, and some months carry none at all. A December with three public holidays can have 18 working days against a March with 22 — a difference of nearly a full working week.
Any month-over-month comparison that ignores this will attribute a capacity artefact to performance. Select your jurisdiction in the calculator and the holidays are excluded automatically, with the count shown separately from the weekend total so you can see which effect is which.
Where it matters most
Capacity planning, invoicing, SLA measurement and payroll accrual all depend on the actual count. So does anything where a monthly target is set once and applied to every month — a per-month target implicitly assumes months are interchangeable, and they are not.
Recruitment and onboarding planning are affected in a subtler way: a start date late in a short month can mean a new joiner has very few working days in their first calendar month, which distorts any first-month expectation.
Making it reproducible
Record the month, the weekday count, the holiday calendar you selected and the resulting net figure. All four are needed for someone else to reproduce the number, and the calendar is the one that changes most often between teams and locations — which is why the result names the calendar it used.
For distributed teams, calculate per location rather than once for the organisation. A shared monthly figure that ignores regional holidays will be wrong for most of the people it describes.
Worked example
None of this is difficult arithmetic. The part worth slowing down for is deciding which convention applies before you start.
Common mistakes to avoid
- Using an average month. The real count varies from 19 to 23 before holidays. Calculate the specific month.
- Comparing monthly output without normalising. Differences in working days look like performance differences. Show the count or normalise per day.
- Applying one holiday calendar to a distributed team. Calculate per location. A single shared figure is wrong for most people it covers.
Use the right calculator
The calculators below apply exactly the method described here, with the assumptions visible on the page.
Frequently asked questions
What is the maximum number of weekdays in a month?
23, in a 31-day month that begins on a Monday. The minimum is 19, in a 28-day February beginning on a Friday.
Does this include public holidays?
Yes, when a jurisdiction is selected. The result separates weekend days from public holidays so you can see the effect of each.
What about a four-day working week?
Adjust the weekend pattern to match, or apply a factor to the weekday count and state which you did.