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Service Inventory Calculator

The Service Inventory Calculator treats available service capacity and committed work as the “inventory” of a service business. It measures how many billable hours remain unsold, how heavily available capacity is utilized, and how many weeks of future capacity are already covered by backlog.

This approach is useful for agencies, repair teams, professional practices, field services, and other operations where time slots or labor hours are the primary sellable resource. It helps managers identify underbooking, near-term capacity pressure, and the risk of accepting more work than the team can deliver. It does not value physical supplies; it focuses on time-based service inventory.

Service assumptions

people
hours
hours
hours
Result
—
Unsold weekly service capacity
Total weekly capacity—
Capacity utilization—
Backlog coverage—

1. Count billable team members
Include people whose capacity is available for the service line being evaluated.

2. Set realistic weekly hours
Use hours available for billable delivery after meetings, leave, training, and nonbillable duties.

3. Enter sold weekly hours
Use hours already assigned or expected to be delivered in the current week.

4. Add committed backlog
Enter contracted work not yet delivered, expressed in the same billable-hour basis.

5. Review utilization and coverage
Unsold hours show immediate availability, while backlog weeks indicate future workload depth.

Weekly capacity = Team members × Available hours per member
Unsold capacity = max(Weekly capacity − Sold hours, 0)
Utilization = Sold hours ÷ Weekly capacity × 100
Backlog coverage = Backlog hours ÷ Weekly capacity

The model assumes every billable hour is interchangeable. Skill constraints, appointment windows, geography, and project sequencing can reduce usable capacity even when aggregate hours appear available.

What the result means

The main result is the number of current-week billable hours that remain available for sale.

Utilization above 100% indicates overbooking relative to the entered capacity, even though unsold capacity is displayed as zero.

Given: 8 billable team members, 32 available hours each, 210 sold hours this week, and 520 backlog hours.

Calculation: Weekly capacity = 8 × 32 = 256 hours. Unsold capacity = 256 − 210 = 46 hours. Utilization = 210 ÷ 256 × 100 = 82.0%. Backlog coverage = 520 ÷ 256 = 2.03 weeks.

Result: The team has 46 unsold hours this week and about 2.03 weeks of backlog.

The operation has some immediate availability but already has roughly two full weeks of future work committed.

Why call service capacity inventory?

Service hours cannot usually be stored after the time period passes, but available slots function like perishable inventory. The calculation makes that capacity visible.

Can utilization exceed 100%?

Yes. That indicates sold hours exceed the stated capacity and may require overtime, subcontracting, schedule changes, or delayed delivery.

Should vacation time reduce available hours?

Yes. Enter the hours actually available in the period after planned leave and nonbillable commitments.

How should different skill groups be handled?

Run separate calculations for teams with different capabilities. Combining them can hide a shortage in a specialized role.

Does backlog coverage predict completion dates?

Only approximately. Project dependencies, priorities, and uneven demand can change actual completion timing.