Man-Hours Calculator 2026
Project Estimation, Labor Tracking & Safety Metrics
Based on OSHA guidelines
What are Man-Hours?
โฑ๏ธ Man-Hours Definition
Man-hours (also called labor-hours or person-hours) is a unit of measurement representing the work done by one person in one hour. It's essential for project estimation, labor cost calculation, and safety tracking in industries like construction, manufacturing, and oil & gas.
Example: If 5 workers each work 8 hours, that's 5 ร 8 = 40 man-hours of work completed.
Man-Hours Calculator
Quick Man-Hours Calculation
Project Labor Estimation
OSHA Safety Calculations
Detailed Worker Entry
Add individual workers or crews with their hours:
๐ Man-Hours Results
Man-Hours Formulas
Basic Man-Hours Formula
Total Man-Hours (Multiple Days)
OSHA Incident Rate (TRIR)
DART Rate (Days Away, Restricted, Transfer)
Estimated Project Duration
- Count Workers: Determine the total number of workers on the project or shift.
- Track Hours: Record total hours worked by each worker or crew.
- Multiply: Man-Hours = Workers ร Hours (do this for each worker/crew and sum).
- Add for Duration: Multiply by work days for multi-day projects.
- Apply Safety Metrics: Use total man-hours for OSHA rate calculations.
Man-Hours Reference Tables
Construction Man-Hours Per Square Foot
| Building Type | Man-Hours/SF | 1,000 SF Estimate | Notes |
|---|---|---|---|
| Single-Family Home | 0.8 - 1.5 | 800 - 1,500 hrs | Basic to custom |
| Multi-Family Housing | 0.6 - 1.0 | 600 - 1,000 hrs | Economies of scale |
| Office Building | 0.5 - 0.9 | 500 - 900 hrs | Shell & core |
| Retail Space | 0.4 - 0.8 | 400 - 800 hrs | Basic fit-out |
| Industrial/Warehouse | 0.2 - 0.5 | 200 - 500 hrs | Simple structures |
| Hospital/Medical | 1.5 - 3.0 | 1,500 - 3,000 hrs | Complex systems |
OSHA Rate Benchmarks by Industry (2024)
| Industry | Avg TRIR | Avg DART Rate | Good Target |
|---|---|---|---|
| Construction (Overall) | 2.8 | 1.5 | < 2.0 |
| Manufacturing | 3.2 | 1.8 | < 2.5 |
| Oil & Gas Extraction | 0.8 | 0.4 | < 0.5 |
| Warehousing | 4.8 | 2.5 | < 3.5 |
| Healthcare | 5.5 | 2.1 | < 4.0 |
| Retail Trade | 3.0 | 1.2 | < 2.0 |
Man-Hours Per Week Reference
| Crew Size | 40-Hour Week | 50-Hour Week | 60-Hour Week |
|---|---|---|---|
| 1 Worker | 40 MH | 50 MH | 60 MH |
| 5 Workers | 200 MH | 250 MH | 300 MH |
| 10 Workers | 400 MH | 500 MH | 600 MH |
| 25 Workers | 1,000 MH | 1,250 MH | 1,500 MH |
| 50 Workers | 2,000 MH | 2,500 MH | 3,000 MH |
| 100 Workers | 4,000 MH | 5,000 MH | 6,000 MH |
OSHA Safety Metrics Explained
๐ TRIR (Total Recordable Incident Rate)
The number of OSHA recordable incidents per 100 full-time workers per year. Formula: (Incidents ร 200,000) รท Man-Hours. Lower is better.
๐ DART Rate
Days Away, Restricted, or Transfer cases per 100 workers. More severe than TRIR. Formula: (DART Cases ร 200,000) รท Man-Hours.
๐ Severity Rate
Lost workdays per 100 workers. Formula: (Lost Days ร 200,000) รท Man-Hours. Measures injury severity rather than frequency.
๐ Accident-Free Man-Hours
Total man-hours worked since the last recordable incident. Used to celebrate safety milestones and track continuous improvement.
Official Resources
Frequently Asked Questions
Man-Hours = Number of Workers ร Hours Worked. Example: 10 workers ร 8 hours = 80 man-hours. For multi-day projects, multiply by number of days: 80 ร 20 days = 1,600 total man-hours.
For OSHA incident rates, use: Rate = (Incidents ร 200,000) รท Total Man-Hours. The 200,000 factor represents 100 full-time employees working 40 hours/week for 50 weeks. Lower rates indicate better safety performance.
Break the project into tasks, estimate hours per task, add contingency (15-25%). For construction, use man-hours per square foot estimates. Example: 2,000 SF ร 1.0 MH/SF = 2,000 man-hours baseline, + 20% contingency = 2,400 total.
In construction, man-hours measure total labor effort for a project. They're used for bidding, scheduling, productivity tracking, and safety reporting. Industry benchmarks range from 0.2-3.0 man-hours per square foot depending on building type.
Track total man-hours worked since the last OSHA recordable incident. Reset to zero after any recordable. Companies celebrate milestones like 100,000 or 1,000,000 accident-free man-hours as safety achievements.
200,000 hours equals 100 employees ร 40 hours/week ร 50 weeks/year. OSHA uses this to standardize incident rates across companies of different sizes, making safety performance comparable.
It varies by industry. Construction average is 2.8; a good target is below 2.0. Oil & gas averages 0.8. World-class performers achieve below 1.0 across industries. Check BLS data for your specific industry benchmark.
They're the same concept. "Person-hours" is the gender-neutral term now preferred by many organizations. All mean: one person working for one hour equals one unit. Use whichever your organization prefers.
Use story points converted to hours, or historical data. Typical ranges: small feature 8-24 hours, medium feature 40-80 hours, major feature 160-320 hours. Add 20-30% for testing, documentation, and meetings.
TRIR counts ALL OSHA recordable incidents. DART only counts the more severe cases involving Days Away from work, Restricted duty, or job Transfer. DART is always lower than or equal to TRIR.
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Last Updated: January 2026