The Monthly Capacity Estimator measures usable work capacity after accounting for availability and a planning reserve. It starts with people, working days, and scheduled hours, then applies an availability rate and removes a buffer for interruptions or uncertainty.
Managers can use the estimate for staffing, backlog planning, sprint forecasting, and service-level discussions. Because the result separates gross hours from usable hours, it also makes assumptions about leave, meetings, and contingency visible instead of hiding them inside a single target.
1. Count contributors
Include people whose time is available to the workload being planned.
2. Enter the month length
Use actual working days after holidays and known absences.
3. Set scheduled daily hours
Enter nominal working time before availability adjustments.
4. Apply availability
Estimate the share remaining after meetings, support, leave, and routine duties.
5. Reserve uncertainty capacity
Hold back a percentage for unplanned demand before committing the balance.
Enter percentage rates as percentages; the calculator converts them to decimals. The model treats availability and reserve as sequential reductions.
Usable hours are the amount that can be committed to planned work after both availability loss and the reserve are applied.
The estimate is only as reliable as the availability assumptions; update them from actual time data when possible.
Given: 6 people, 22 days, 8 scheduled hours, 75% availability, and a 10% reserve.
Calculation: Gross hours = 6 × 22 × 8 = 1,056. Available hours = 1,056 × 0.75 = 792. Reserved hours = 792 × 0.10 = 79.2. Usable hours = 792 − 79.2 = 712.8.
Result: Plan against 712.8 usable hours for the month.
No. Availability estimates time that could be used for planned work; utilization measures how much capacity is actually used.
Either reduce working days or lower availability, but avoid counting the same leave twice.
Yes, although a zero reserve leaves no modeled room for unexpected demand.
The reserve protects the capacity that remains genuinely available, not time already lost to other activities.
Yes. Set team members to one and use that person’s working days and availability assumptions.