How do you calculate the cost of a custom part?

Multiply the order quantity by the variable cost per part, then add the fixed setup, tooling, and engineering cost. For 650 parts at $24.60 each plus $3,900 fixed, the total is (650 × $24.60) + $3,900 = $19,890.

What is the effective per-piece cost?

Divide total job cost by quantity. Here $19,890 over 650 parts is about $30.60 per piece — notably higher than the $24.60 variable cost because the $3,900 of fixed cost spreads across only 650 parts.

Why does the per-piece cost exceed the variable cost?

Because fixed setup, tooling, and engineering are amortized over the run. At 650 parts the $3,900 fixed cost adds $6.00 per piece. Double the quantity and that fixed share would halve to $3.00.

What counts as fixed cost on a custom part?

One-time costs that do not repeat per piece: CNC programming, fixture and tooling fabrication, first-article inspection, and engineering review. They are incurred once whether you make 1 part or 1,000.

How does quantity change my quote?

Higher quantity dilutes fixed cost across more pieces, lowering the effective per-piece price, while variable cost per part stays roughly flat. That is why customers asking for more parts often get a lower unit price.

Should I quote variable cost or total cost?

Quote from total cost, then divide by quantity for the per-piece price the customer sees. Quoting off variable cost alone leaves the $3,900 of setup and tooling unrecovered.

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

Custom Part Cost Calculator

Custom Part Cost gives a job shop the total cost of a make-to-order run by separating the variable cost that scales with quantity from the one-time fixed cost of setup, tooling, and engineering. Estimators use it to build a defensible quote and to see how fixed cost spreads as quantity rises, which is exactly where short runs lose money. It matters because customers compare per-piece prices, but your real cost structure is variable-plus-fixed — and pricing as if it were purely variable is how shops underquote tooling-heavy parts. This calculator computes the variable cost across the quoted quantity, adds the fixed cost, and shows the effective per-piece cost.

What this calculator does

Estimate total cost for a customer-specific part or assembly.
building a quote from material, routing, setup, tooling, inspection, and outside service assumptions
It multiplies order quantity by variable cost per part (scaled by the share of scope costed), then adds fixed setup, tooling, and engineering cost to produce total job cost and an effective per-piece figure.

Formula used

Variable custom part cost = quoted part order quantity × variable cost per custom part × costed quote scope included
Total custom part cost = variable custom part cost + fixed setup, tooling, and engineering cost

Inputs explained

Quoted part order quantity:
Variable cost per custom part:
Costed quote scope included:
Fixed setup, tooling, and engineering cost:

How to use the result

Use it when building a quote for a custom or one-off part where setup and tooling are significant relative to the run size.
It treats variable cost per part as flat across the quantity; if your material or cycle cost steps down with volume, costed scope below 100%, or partial tooling reuse, you must adjust the inputs to reflect that.

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 the cost of a custom part? Multiply the order quantity by the variable cost per part, then add the fixed setup, tooling, and engineering cost. For 650 parts at $24.60 each plus $3,900 fixed, the total is (650 × $24.60) + $3,900 = $19,890.
What is the effective per-piece cost? Divide total job cost by quantity. Here $19,890 over 650 parts is about $30.60 per piece — notably higher than the $24.60 variable cost because the $3,900 of fixed cost spreads across only 650 parts.
Why does the per-piece cost exceed the variable cost? Because fixed setup, tooling, and engineering are amortized over the run. At 650 parts the $3,900 fixed cost adds $6.00 per piece. Double the quantity and that fixed share would halve to $3.00.
What counts as fixed cost on a custom part? One-time costs that do not repeat per piece: CNC programming, fixture and tooling fabrication, first-article inspection, and engineering review. They are incurred once whether you make 1 part or 1,000.
How does quantity change my quote? Higher quantity dilutes fixed cost across more pieces, lowering the effective per-piece price, while variable cost per part stays roughly flat. That is why customers asking for more parts often get a lower unit price.

Last reviewed 2026-05-12.