Count Workdays in a Semimonthly Pay Period

A semimonthly calendar commonly divides the month into two periods, such as the first through the fifteenth and the sixteenth through month-end. Those periods do not necessarily contain the same number of weekdays. Count the actual dates and scheduled hours rather than dividing monthly hours in half.

Define both period boundaries

Use the employer's actual period start and end dates, with an explicit inclusive rule. The example here includes both endpoints and assumes a Monday-to-Friday schedule, eight hours per scheduled day and no closures. It does not assume that payment occurs on the period's final day.

Consider February 2027. February 1 is a Monday and the month has 28 days. February 1–15 contains 11 Monday-to-Friday days; February 16–28 contains nine. At eight hours per weekday, the periods contain 88 and 72 scheduled hours, totaling 160 for the month.

February 2027 example without closures
Period	Weekdays	Hours at eight per day
February 1–15 inclusive	11	88
February 16–28 inclusive	9	72
Whole month	20	160

Subtract only relevant closures

If the organization closes for one eight-hour weekday in the first period, available scheduled work becomes 80 hours there. If a closure falls on an already nonworking Sunday, subtracting another eight hours would double-count the nonworking time. Use the intersection of closure dates and scheduled workdays.

Keep available work hours separate from paid hours. A paid closure may reduce operational availability without reducing the employee's paid-hours figure. Your column labels should identify which measure the calculation represents.

Use individual schedules for irregular work

A weekday count is not enough for a rotating shift employee, a four-day schedule or a person with different hours on different days. Sum that person's scheduled net hours between the period boundaries. The same month can have different period totals for different schedules.

If a shift crosses midnight at the boundary, apply the organization's allocation rule consistently. Do not count the full shift in both halves of the month. Preserve start and end timestamps so a reviewer can reproduce any split.

Do not infer salary allocation from hours

Unequal scheduled hours do not automatically imply unequal salaried semimonthly payments. The payment arrangement is a separate input. This calculation is useful for capacity, timekeeping reconciliation and planning; it does not establish how salary should be prorated.

For a calendar check, add the two period totals and compare them with the whole-month schedule. Any difference signals an omitted date, overlapping boundary, inconsistent closure treatment or a different schedule assumption.

Frequently asked questions

Is every semimonthly period 15 days long?

No. With a first-to-fifteenth split, the second period's calendar-day count varies with month length. Other employers can use different boundaries.

Can I use 86.67 hours for every period?

That is an average derived from 2,080 hours divided by 24, not an actual date count. Use it only when that average is the intended measure, and label it accordingly.

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