40 hours per week × 52 weeks ÷ 12 months = about 173.33 scheduled hours per month as an annualized planning average.
The common 40-hour answer: about 173.33 hours per month
A 40-hour weekly schedule averages about 173.33 scheduled hours per month when you annualize the schedule: 40 hours × 52 weeks ÷ 12 months = 173.33 hours.
That is a planning average, not the exact number of working hours in every calendar month. Months contain different numbers of weekdays, and work schedules, holidays, PTO, and unpaid time vary.
Monthly work-hours formula
For a stable weekly schedule, estimated monthly scheduled hours = weekly hours × 52 ÷ 12. This uses the full-year weekly schedule and spreads it evenly across 12 months.
Because 52 ÷ 12 is about 4.333, another equivalent shortcut is weekly hours × 4.333.
| Weekly schedule | Annual scheduled hours | Average per month |
|---|---|---|
| 20 hours | 1,040 | 86.67 |
| 25 hours | 1,300 | 108.33 |
| 30 hours | 1,560 | 130.00 |
| 35 hours | 1,820 | 151.67 |
| 37.5 hours | 1,950 | 162.50 |
| 40 hours | 2,080 | 173.33 |
Why some months have more work hours than others
Calendar months do not contain the same number of weekdays. A Monday-through-Friday employee can have more scheduled workdays in one month than another, so actual scheduled hours can be above or below the 173.33 annualized average.
For an exact month, count the employee's scheduled workdays in that month and multiply by scheduled hours per day, then adjust for any schedule exceptions that matter to the calculation.
Example: a 22-workday month
An eight-hour-per-day schedule across 22 scheduled workdays equals 176 scheduled hours. A 20-workday month at the same daily schedule equals 160 hours.
Both can occur even though the annualized 40-hour-week average is 173.33 hours per month. The average is useful for planning; the calendar count is better for month-specific scheduling.
Does full time always mean 40 hours per week?
No. The Department of Labor states that the FLSA does not define full-time or part-time employment. Employers generally determine those labels, while other laws and statistical programs can use purpose-specific definitions.
Use the actual weekly schedule instead of assuming 40 hours whenever you need a personal estimate. For more detail, see How Many Hours Is Full Time?
Monthly work hours vs monthly salary
A fixed annual salary divided by 12 gives a monthly salary amount, but that does not mean every month contains the same number of work hours. Salary and calendar-hour calculations answer different questions.
If you are converting compensation, keep the salary formula and work-hour assumptions explicit rather than forcing the exact calendar hours into a simple salary conversion.
Monthly hours vs annual hours
Annual scheduled hours are calculated directly from weekly hours × weeks per year. Monthly average hours divide that annual figure by 12.
For the annual reference, see How Many Work Hours Are in a Year? For exact shift duration, use the Hours Worked Calculator.
Use the related calculators
Use the Hours Worked Calculator for a specific shift, the Hourly to Salary Calculator for annualized compensation, and the Monthly Salary Calculator for annual salary divided into a monthly equivalent.
These tools calculate from the assumptions you enter and do not define an employer's required schedule.
Continue with a calculation