How do you calculate job shop capacity?

Multiply parts per scheduled slot by available slots to get gross capacity, then multiply by uptime and first-pass yield. With 24 parts/slot over 160 slots at 78% uptime and 94% yield, gross is 3,840 parts and good capacity is 2,815 parts.

What is the difference between gross and good capacity?

Gross scheduled capacity (3,840 parts here) is what the schedule says the machines could make if nothing went wrong. Good capacity (2,815 parts) is what survives downtime and scrap — the number you should actually promise to a customer.

Why is so much capacity lost?

In this example 845 parts are lost to uptime limits and 180 to scrap and rework. Uptime almost always dominates: a 78% uptime shaves off more than four times the parts that a 94% yield does, which is why chasing machine availability usually beats chasing yield.

What is a good uptime for a job shop?

Well-run job shops typically run 80-90% scheduled uptime; 78% leaves room to improve. Heavy setup-to-run ratios on short make-to-order jobs naturally pull uptime down, so benchmark against shops with similar lot sizes, not high-volume production lines.

Should I quote lead times off gross or good capacity?

Always good capacity. If you load the schedule to 3,840 parts but only deliver 2,815 good ones, every job slips. Plan the backlog against the 2,815 figure and treat the gap as the buffer you've already paid for.

Contract Manufacturing, Job Shop Quoting & Make-to-Order calculator

Job Shop Capacity Calculator

Job shop capacity tells you how many good, sellable parts a make-to-order shop can realistically produce in a planning window once downtime and scrap are subtracted. Estimators and production planners in CNC, fabrication, and contract machining shops use it to commit promise dates and decide whether to accept a rush RFQ or quote a longer lead time. The number that matters is not the machine's nameplate throughput but the good capacity that survives real-world uptime and first-pass yield. Quote against gross capacity and you over-promise; quote against good capacity and your delivery dates hold.

What this calculator does

Estimate good-part capacity for a job shop or make-to-order work center.
checking whether the shop can accept more RFQs, orders, or rush jobs in a capacity window
It computes good (sellable) job-shop capacity by multiplying gross scheduled capacity by expected uptime and first-pass yield, and breaks out the parts lost to each.

Formula used

gross scheduled job-shop capacity = parts per scheduled production slot × available production slots
good job-shop capacity = gross scheduled job-shop capacity × expected shop uptime × expected first-pass yield

Inputs explained

Parts per scheduled production slot:
Available production slots:
Expected shop uptime:
Expected first-pass yield:

How to use the result

Use it when you are committing a delivery date on an RFQ, sizing a backlog against finite machine hours, or deciding whether to subcontract overflow work.
It assumes a single representative slot rate and uniform uptime and yield; a mixed job queue with widely different cycle times or setup-heavy short runs will need a weighted or per-job estimate instead.

Current U.S. benchmarks

The U.S. prime lending rate is 6.75% (Federal Reserve via FRED, 2026-07-02). Payback and financing math should start from today's rate, not a remembered one.

Common questions

How do you calculate job shop capacity? Multiply parts per scheduled slot by available slots to get gross capacity, then multiply by uptime and first-pass yield. With 24 parts/slot over 160 slots at 78% uptime and 94% yield, gross is 3,840 parts and good capacity is 2,815 parts.
What is the difference between gross and good capacity? Gross scheduled capacity (3,840 parts here) is what the schedule says the machines could make if nothing went wrong. Good capacity (2,815 parts) is what survives downtime and scrap — the number you should actually promise to a customer.
Why is so much capacity lost? In this example 845 parts are lost to uptime limits and 180 to scrap and rework. Uptime almost always dominates: a 78% uptime shaves off more than four times the parts that a 94% yield does, which is why chasing machine availability usually beats chasing yield.
What is a good uptime for a job shop? Well-run job shops typically run 80-90% scheduled uptime; 78% leaves room to improve. Heavy setup-to-run ratios on short make-to-order jobs naturally pull uptime down, so benchmark against shops with similar lot sizes, not high-volume production lines.
Should I quote lead times off gross or good capacity? Always good capacity. If you load the schedule to 3,840 parts but only deliver 2,815 good ones, every job slips. Plan the backlog against the 2,815 figure and treat the gap as the buffer you've already paid for.

Last reviewed 2026-05-12.