Man-Hours Calculator — Project Labour Effort
Estimate the total labour effort for any project — from a construction job to a software sprint — by entering the number of workers, hours worked per day, and the project duration in days. Optionally add an hourly rate to get the total labour cost.
hrs
days
$/hr
Workers × hours per day × days
- 1
Hours per worker-day
5 workers × 8 hrs = 40 - 2
Total man-hours
40 × 20 days = 800
How does this calculator work?
Man-hours = workers × hours per day × days. This is the total labour effort in person-hours. Multiply by an hourly wage to get the estimated labour cost. Man-days = workers × days. Both are planning baselines — add 10–20% contingency for real-world variability in productivity.
Formula
How this is calculated
A man-hour (or person-hour) is the work performed by one worker in one hour. It is the standard unit of labour effort in project management, construction and manufacturing. The total man-hours for a project is simply the product of the number of workers, the hours each works per day, and the number of working days in the project schedule.
Man-days (the total number of full worker-days) are calculated as workers × days, useful for comparing projects where the daily hours may vary. Multiplying total man-hours by the average hourly cost of labour gives a first-order estimate of direct labour cost — this excludes overhead, benefits, materials and equipment.
This simple linear model assumes all workers work the same hours every day and are equally productive throughout the project. In practice, productivity varies with task type, weather, learning curves and fatigue. Use the result as a planning baseline and apply an appropriate contingency factor (commonly 10–20%) for bidding or budgeting.
Frequently asked questions
A man-hour (or person-hour) represents the amount of work performed by one person working for one hour at a sustainable rate. It is used to measure and compare labour effort independently of how many workers are assigned or how long the project lasts.
Man-hours count total hours worked across all workers; man-days count total working days (workers × days). One man-day equals however many hours constitute a standard shift — commonly 8 hours. Man-hours are more precise when shifts vary; man-days are useful for scheduling at the day level.
Divide the total man-hours by the number of hours available per worker for the project period. For example, 400 man-hours over a 4-week (20-day) project with 8-hour days requires 400 ÷ (20 × 8) = 2.5 workers — round up to 3 for a realistic staffing plan.
Also known as
TG we-Calculate Editorial Team. (2026). Man-Hours Calculator — Project Labour Effort [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/man-hours-calculator
TG we-Calculate Editorial Team. "Man-Hours Calculator — Project Labour Effort." TG we-Calculate. 2026. https://we-calculate.com/calculator/man-hours-calculator.
TG we-Calculate Editorial Team, "Man-Hours Calculator — Project Labour Effort," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/man-hours-calculator
@misc{wecalculate_man_hours_calculator, title = {Man-Hours Calculator — Project Labour Effort}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/man-hours-calculator}}, year = {2026}, note = {TG we-Calculate} }
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