Workforce planning · Person-hours arithmetic
How to calculate man-hours without double-counting
Total worked or planned person-hours for a group with the same schedule.
By HSECalc · Published
Check that this method fits your task
Use actual hours for reporting. This schedule-based total is an estimate unless reconciled with attendance and time records.
Choose your inputs and work through the steps
- Separate people into groups with the same schedule. Record the period and whether the figures are planned or reconciled actual time.
- Enter workers, days per worker and scheduled hours per day. Subtract non-working time once; do not subtract it again if your starting hours already exclude breaks.
- Add overtime as a whole-group total only when it is not already in the schedule. For mixed shifts, calculate each group separately and sum the results.
Total = workers × days × (scheduled hours − non-working hours) + additional group hours.
A worked example
Illustrative values explain the tool; they are not prescribed inputs for your work.
- 8 − 0.5 = 7.5 worked hours per person per day.
- 10 × 5 × 7.5 = 375 person-hours.
- 375 + 25 additional group hours = 400 person-hours.
Read the result and decide what needs checking
Keep the attendance or time-record reconciliation with the total. A neat schedule calculation does not confirm that everybody worked every planned shift.
When using the total in a KPI, match the employees and period to the case count. Compare person-hours with person-days only after stating the hours-per-day definition.
Common questions
Are man-hours and person-hours the same?
Yes. One person working one hour contributes one person-hour.
What about different shifts?
Calculate each group separately and add their totals. Do not use a single schedule for people who worked different hours.
Can I use the result in TRIR or DART?
Use reconciled actual hours for the same workforce and reporting period as the cases, following the applicable reporting method.
References and scope notes
Use the current official guidance and the instructions for your actual equipment. HSECalc is independent; a reference is not an endorsement. Read how we use methods and sources or report a correction.