How do you calculate cost per part for finishing?

Multiply quantity by the cost rate, divide by the billable share because unbillable finishing time still costs the shop, add fixed cost, then divide by quantity. With 100 parts at $45, an 80% billable share, and $250 fixed, total is $5,875 and per-piece cost is $58.75.

Why does cost per part drop as quantity rises?

The fixed setup and media cost, $250 here, is spread over more parts. At 100 parts it adds $2.50 each; at 1,000 parts it would add only $0.25, lowering the per-piece figure.

What does the billable share factor do?

It captures the portion of the cost rate that is actually chargeable or recoverable. At 80% the run's variable cost loads from $4,500 to $5,625, because the unrecovered share is still spent before fixed cost is added.

What is a good cost per part for deburring?

It varies widely by part size and tolerance, but the goal is a per-piece cost low enough to leave healthy margin after quoting. Track it over time; a rising number signals creeping setup or media cost.

How do I lower cost per part?

Increase batch size to dilute the $250 fixed cost, raise the billable share by cutting non-chargeable time, or reduce the per-part rate with faster cycles and better media-to-part ratios.

Cost per part vs quote price, what's the difference?

Cost per part is your internal floor. Quote price applies margin on top. Use this calculator to know cost, then mark it up before presenting a price to the customer.

Mass Finishing, Deburring & Polishing calculator

Cost Per Part Calculator

Cost per part breaks the true cost of deburring or polishing a component into the variable processing cost that scales with volume plus the fixed setup and media cost spread across the run. Estimators and finishing-cell owners use it to know their real floor before quoting and to see how per-piece cost falls as quantities rise. Because mass finishing carries heavy fixed costs, media charge, compound, and machine setup, the per-part number swings sharply with batch size. This calculator makes that trade-off explicit so you never quote below cost on a small job.

What this calculator does

Calculate cost per part for mass finishing, deburring & polishing planning, quoting, troubleshooting, capacity review, or process improvement.
Use it when cost per part in mass finishing, deburring and polishing is being put through a mass finishing, deburring and polishing weighted-cost review.
It computes total finishing cost as quantity times rate times billable share plus fixed cost, then divides by quantity for per-piece cost.

Formula used

Cost Per Part cost = quantity × rate × capture factor + fixed cost
Per-unit cost per part = total cost ÷ quantity

Inputs explained

Parts finished in the run:
Finishing cost rate per part:
Billable share of finishing cost:
Fixed setup and media cost:

How to use the result

Use it when costing a deburring or polishing job before applying margin, or to find the breakeven batch size.
It uses a single blended cost rate; multi-step processes with different rates per operation should be costed stage by stage.

Common questions

How do you calculate cost per part for finishing? Multiply quantity by the cost rate, divide by the billable share because unbillable finishing time still costs the shop, add fixed cost, then divide by quantity. With 100 parts at $45, an 80% billable share, and $250 fixed, total is $5,875 and per-piece cost is $58.75.
Why does cost per part drop as quantity rises? The fixed setup and media cost, $250 here, is spread over more parts. At 100 parts it adds $2.50 each; at 1,000 parts it would add only $0.25, lowering the per-piece figure.
What does the billable share factor do? It captures the portion of the cost rate that is actually chargeable or recoverable. At 80% the run's variable cost loads from $4,500 to $5,625, because the unrecovered share is still spent before fixed cost is added.
What is a good cost per part for deburring? It varies widely by part size and tolerance, but the goal is a per-piece cost low enough to leave healthy margin after quoting. Track it over time; a rising number signals creeping setup or media cost.
How do I lower cost per part? Increase batch size to dilute the $250 fixed cost, raise the billable share by cutting non-chargeable time, or reduce the per-part rate with faster cycles and better media-to-part ratios.

Last reviewed 2026-08-12.