Find total man-hours and labor cost, or solve for how many people you need
💡 Why This Matters Man-hours turn "how many people, how long" into one clean number you can use to budget a project or figure out exactly how much staffing you need to hit a deadline.
🔄 Or, work backward: know your deadline, not your headcount?
The man-hour concept is the backbone of workplace safety tracking, too — OSHA's injury rate formula uses total man-hours as its baseline, with 200,000 man-hours representing roughly 100 full-time employees working a full year.
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Man-hours is the number of people working multiplied by the hours each of them works: man-hours = people × hours. If you provide an hourly pay rate, total labor cost is simply man-hours × hourly pay. Working backward, if you know your total man-hours needed and how many hours you have to finish, dividing gives you the number of people required: people needed = man-hours ÷ hours available.
Man-hours is a normalized measure of total labor effort — five people working eight hours produces the same 40 man-hours as one person working 40 hours. That makes it useful for comparing projects of different team sizes or estimating cost and staffing on a like-for-like basis.
This calculator assumes every worker is equally productive and paid the same rate, which real teams rarely are. If your team has mixed pay rates or very different skill levels, treat this as a rough planning estimate and calculate cost per person separately for more precision.
Use the forward calculation to budget a project once you know your team size and schedule. Use the reverse calculation when you know a deadline and total workload but need to figure out how many people to hire or assign — a common question when scoping a new project against a fixed timeline.
Forward example: Say you have 5 people each working 8 hours at $25/hour. Man-hours: 5 × 8 = 40 man-hours. Total cost: 40 × $25 = $1,000.
Reverse example: Say a project needs 400 man-hours total, and you only have 80 hours to get it done. People needed: 400 ÷ 80 = 5 people.
A man-hour is the amount of work one person can complete in one hour. Five people working eight hours each equals the same 40 man-hours as one person working 40 hours — it's a way to measure total labor effort regardless of team size.
Enter your total man-hours needed and how many hours are available to complete the work, and the calculator solves for how many people it takes. This is the reverse of the standard calculation — useful when you know the deadline but not the headcount.
Not quite. Man-hours measures total labor time contributed, while billable hours refers specifically to the hours a client is charged for. All billable hours are man-hours, but not all man-hours end up billable — some go to internal tasks, training, or overhead.
Total labor cost is simply man-hours multiplied by hourly pay. If pay rates differ between workers, calculate each person's contribution separately and add the totals together for an accurate cost.