Schedule Duration Calculator
Plan your construction cost project with our free schedule duration calculator. Get precise measurements, material lists, and budgets.
Formula
Work Days = (Man-Hours / Productivity%) / (Crew Size x Hours/Day)
Divide the total estimated man-hours by the productivity factor to get adjusted man-hours. Then divide by the daily crew output (crew size multiplied by hours per day) to calculate the number of work days. Convert to calendar days by accounting for non-work days in the week. Add weather and contingency factors for a realistic completion estimate.
Worked Examples
Example 1: Residential Framing Schedule
Problem: Estimate duration for 2,400 man-hours of framing work with a 6-person crew, 8 hours/day, 5 days/week, 80% productivity.
Solution: Adjusted hours = 2,400 / 0.80 = 3,000\nCrew hours/day = 6 x 8 = 48\nWork days = ceil(3,000 / 48) = 63 days\nWeeks = 63 / 5 = 12.6 weeks\nCalendar days = ceil(63 x 7/5) = 89 days
Result: 63 work days (12.6 weeks, ~89 calendar days)
Example 2: Commercial Electrical Rough-In
Problem: Calculate duration for 6,000 man-hours with a 10-person crew, 10 hours/day, 6 days/week, 85% productivity.
Solution: Adjusted hours = 6,000 / 0.85 = 7,059\nCrew hours/day = 10 x 10 = 100\nWork days = ceil(7,059 / 100) = 71 days\nWeeks = 71 / 6 = 11.8 weeks\nCalendar days = ceil(71 x 7/6) = 83 days
Result: 71 work days (11.8 weeks, ~83 calendar days)
Frequently Asked Questions
What is a productivity factor and how does it affect schedule duration?
The productivity factor represents the percentage of time workers are actually productive versus the total paid time. An 85% productivity factor means that for every 8-hour day, workers produce 6.8 hours of effective work. The remaining time is consumed by breaks, tool handling, travel within the site, receiving instructions, and material handling. Extreme weather, cramped work areas, and overtime fatigue further reduce productivity. Dividing the base man-hours by the productivity factor gives the adjusted hours needed, which directly increases the schedule duration.
Can adding more workers reduce the project duration proportionally?
Adding workers does not reduce duration linearly due to the law of diminishing returns. Doubling a crew from 4 to 8 workers rarely halves the schedule because of increased coordination overhead, limited work face availability, trade stacking, and material delivery constraints. Productivity per worker typically decreases by 10-15% when crews exceed the optimal size for the work area. The critical path method (CPM) should guide staffing decisions, as adding workers to non-critical activities does not shorten the overall project. Focus additional labor on critical path activities where the space and logistics support efficient work.
What formula does Schedule Duration Calculator use?
The formula used is described in the Formula section on this page. It is based on widely accepted standards in the relevant field. If you need a specific reference or citation, the References section provides links to authoritative sources.
Is Schedule Duration Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.
How accurate are the results from Schedule Duration Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.