Man-Hours Calculator
Estimate the total man-hours of a job or project from the number of workers, hours per worker per day and the number of days.
Input Data
Results
At a glance:Man-hours measure total labour input. Total man-hours = workers × hours per worker per day × days, giving the combined working hours of the whole team over the project.
Formula
Total man-hours = workers × hours per day × days.
$$\\text{ManHours} = N \\times h \\times d$$How to Use
- Enter the number of workers.
- Enter the average hours each worker puts in per day.
- Enter the project duration in days to see total man-hours.
FAQ
Can I use man-hours to estimate labour cost?
Yes. Multiply total man-hours by the average hourly wage to get a rough labour cost. For example, 1,280 man-hours at an average wage of HK$120 gives about HK$153,600 in labour. This is a common way to price by the hour and build a staffing budget, but remember to add overtime, benefits and management costs on top.
Does adding more workers shorten the schedule proportionally?
Not necessarily. The man-hour multiplication assumes labour is perfectly additive, but in practice adding people brings communication, coordination and learning-curve overhead, so the schedule may not shrink in proportion. Some tasks also have sequential dependencies that cannot be parallelised. This is the well-known 'mythical man-month' lesson — treat such estimates with caution.
Should I enter actual or nominal hours per worker per day?
Use the actual productive hours — the time really spent on the task after deducting breaks, meetings and non-productive time — so the estimate stays realistic. If you enter nominal hours (e.g. a full 8 hours), the total will be optimistic and you should add a buffer when scheduling.
What is the difference between man-hours, man-days and man-months?
They are all units combining labour and time, differing only in granularity. Man-hours use hours (finest, good for short or priced-by-hour work); man-days use a standard working day (e.g. 8 hours), good for mid-size project scheduling; man-months use months, common for large multi-month projects. They convert into each other once you fix 'how many hours per day / days per month'. All share the same limitation that labour is not perfectly additive.
How do I work backwards from man-hours to staff or schedule?
With total man-hours known: days needed = total ÷ (workers × hours per day); or workers needed = total ÷ (hours per day × days). For example, 1,280 man-hours with 10 workers at 8 hours/day needs 16 days; the same 1,280 in 10 days at 8 hours/day needs 16 workers. Multiply by the wage to compare a 'more staff, faster' plan against a 'fewer staff, longer' plan. Remember these are theoretical lower bounds — real constraints usually need a buffer.
Related Tools
References
Content review: Calculatorism Finance Team. Results are for reference only; please refer to the relevant authorities for the official figures.