Contractor field notes
Choose a feasible crew by modeled cost, not headcount alone
This optimizer checks every whole crew size from one to your available maximum. It estimates daily output with a user-defined congestion factor, rounds production to paid whole working days, adds site overhead and per-worker setup cost, and finds the lowest-cost size that meets the deadline. If none qualifies, it reports infeasibility instead of promising an achievable schedule.
Compare each crew size within the same deadline
Daily output(n) = n × hours/day × baseline units/hour × efficiency ÷ [1 + congestion factor × (n − 1)]. Working days = round up(quantity ÷ output). Total cost = days × (n × hours/day × loaded hourly cost + site overhead/day) + n × setup cost. Minimize total cost among crew sizes meeting the deadline.
Worked example
For 3,600 units, 15 units per worker-hour, eight-hour days, 100% base efficiency, and a 3% congestion factor, five workers produce 5 × 8 × 15 ÷ 1.12 = 535.71 units/day. Production requires seven whole working days. At $35/hour, $200/day site overhead, and $100 setup per worker, cost is 7 × ($1,400 + $200) + $500 = $11,700. Of crew sizes one through 20, five is the lowest modeled-cost option meeting a ten-day deadline. Four workers take nine days and cost $12,280.
Common estimating pitfalls
- Do not interpret the congestion input as measured industry-standard performance.
- Whole final days are paid in this model; partial-day billing can change the best crew size.
- A cost optimum does not verify site capacity, supervision, equipment availability, or trade sequencing.
Frequently asked questions
What happens if no crew can meet my deadline?
The result explicitly says the deadline is not met and shows the fastest modeled crew within your range. It does not present that crew as a feasible recommendation.
How are equal-cost crews handled?
Among feasible crews with exactly equal modeled costs, the smaller crew is selected. For the fastest infeasible fallback, equal working-day durations also prefer fewer workers.
Does adding workers always make the job cheaper?
No. More workers can reduce duration but increase paid labor and setup expense, and congestion reduces output gains. The scenario comparison shows each size’s duration, cost, and deadline status.