Man-Hours Calculator
Calculate total man-hours for a project by multiplying the number of workers by hours worked per day and the number of working days. Useful for project planning, payroll, and labor cost estimation.
How to use this tool
- Enter number of workers, hours worked per day and number of working days in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your total man-hours and the full breakdown beneath it.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
Man-Hours = Workers × Hours per Day × Days
Man-Days = Man-Hours ÷ 8
How it works
Man-hours (also called person-hours) quantify the total labor effort on a project by multiplying the workforce size by the hours each person works per day and the total number of working days. Man-days normalize man-hours to standard 8-hour workdays, providing a common unit for project scheduling and cost estimation.
Worked example
10 workers, 8 hours/day for 22 working days
- Workers = 10, Hours per Day = 8, Days = 22
- Total Man-Hours = 10 × 8 × 22 = 1,760 man-hours
- Man-Days = 1,760 ÷ 8 = 220 man-days
- Hours per Worker = 8 × 22 = 176 hours
Total Man-Hours = 1,760; Man-Days = 220; Hours per Worker = 176
Common mistakes to avoid
- Treating man-hours as interchangeable with person-hours of productive output without accounting for breaks, meetings, and administrative time that reduce effective working hours.
- Omitting overtime: if workers log more than 8 hours in a day, the formula still counts all hours as man-hours, but payroll cost calculations must distinguish regular and overtime rates separately.
- Confusing man-days with calendar days — a man-day is 8 hours of work by one person, not a calendar day; a project taking 80 man-days could be completed in 10 calendar days by 8 workers.
Key terms
- What is a man-hour?
- A man-hour (or person-hour) is the amount of work performed by one person working for one hour. It is the standard unit for measuring labor effort in project management.
- What is a man-day?
- A man-day represents one person working for one full standard workday, typically defined as 8 hours. It is used for project planning and scheduling.
- How are man-hours used in cost estimation?
- Total man-hours multiplied by the hourly wage rate gives the direct labor cost for a project, making it essential for budgeting and contract pricing.
- What is the difference between man-hours and labor hours?
- Man-hours and labor hours are used interchangeably. The term 'person-hours' is the gender-neutral equivalent. All refer to work effort measured in worker-hour units.
Frequently asked questions
- How do I convert man-hours to a project cost estimate?
- Multiply total man-hours by the blended hourly labor rate (including benefits and overhead). For example, 500 man-hours at a fully loaded rate of $45/hour gives a direct labor cost of $22,500.
- What is the difference between man-hours and effort hours?
- They are the same concept — total hours of human work applied to a task. Project management literature often uses effort hours to distinguish from elapsed time (duration), which depends on how many workers are assigned.
- Can I use this formula for part-time workers?
- Yes. Simply use the actual hours per day each part-time worker works. If three workers each work 4 hours per day for 10 days, the total is 3 x 4 x 10 = 120 man-hours.