How do you calculate unit assembly cost?

Multiply quantity by the per-unit rate by the capture factor, add fixed cost, then divide by quantity. For 100 units at $45 x 80% plus $250 fixed, total is $3,850 and per-unit is $38.50.

What does the capture factor represent here?

It scales the nominal rate for yield and process efficiency. At 80% capture, the effective assembly value applied is 80% of the raw rate, reflecting that not every hour or part converts cleanly into a shippable unit.

Why is per-unit cost lower than the raw rate in the example?

Because the 80% capture factor pulls the $45 rate down to $36 of captured value per unit, and only the $250 fixed cost adds back, netting $38.50 per unit across 100 units.

How does batch size change per-unit cost?

Fixed cost is spread over more units as quantity rises, so per-unit cost falls. The same $250 setup adds $2.50/unit at 100 units but $25/unit at just 10 units.

Should overhead go in the rate or the fixed cost?

Put variable overhead that scales with each unit into the rate, and one-time setup, fixturing and programming into fixed cost, so batch-size effects come out correctly.

What is a good capture rate for pump assembly?

Mature rotating-equipment lines often run 90-97% first-pass; 80% signals meaningful rework or scrap on seals, balancing or leak test and is worth a root-cause review.

Pump, Compressor & Rotating Equipment Assembly calculator

Unit Assembly Cost Calculator

Unit Assembly Cost tells a rotating-equipment shop what one finished pump or compressor actually costs to build once yield and fixed setup are folded in. Cost estimators and production managers use it to quote jobs, set transfer prices and decide batch sizes. The capture-rate factor is the key twist: assembling rotating equipment involves scrapped seals, re-balanced rotors and failed leak tests, so a nominal per-unit rate rarely equals delivered cost. Adding fixed tooling and setup then spreads one-time cost across the run so small batches don't look artificially cheap.

What this calculator does

Unit Assembly Cost tells a rotating-equipment shop what one finished pump or compressor actually costs to build once yield and fixed setup are folded in.
Use it when unit assembly cost in pump, compressor and rotating equipment assembly is being put through a pump, compressor and rotating equipment assembly weighted-cost review.
It computes total run cost as quantity x rate x capture factor plus fixed cost, then divides by quantity for a true per-unit assembly cost.

Formula used

Unit Assembly Cost cost = quantity × rate × capture factor + fixed cost
Per-unit unit assembly cost = total cost ÷ quantity

Inputs explained

Pumps or compressors assembled in the run:
Direct assembly labor and parts cost per unit:
Yield / good-unit capture rate:
Fixed tooling and setup cost for the run:

How to use the result

Use it when quoting an assembly job, comparing batch sizes, or building a standard cost for a pump or compressor part number.
The single capture factor lumps yield loss and process efficiency into one number; if scrap and rework have very different costs, model them separately for accuracy.

Current U.S. benchmarks

Industrial electricity averages 8.66 cents per kWh across the U.S. (EIA, Apr 2026), up 5.5% from a year earlier. Energy-intensive steps carry this directly into unit cost.
Manufacturing hourly earnings average $30.27 (BLS, Jun 2026), up 4.4% from a year earlier. Median machinist pay is $28.24/hr (OEWS 2025), with state medians on each state page. Manufacturers have 529k open positions nationally (BLS JOLTS).
Steel mill PPI stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. New factory orders are up 2.3% year over year (Census).
The U.S. has 21,668 machinery manufacturing establishments employing about 1,086,146 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate unit assembly cost? Multiply quantity by the per-unit rate by the capture factor, add fixed cost, then divide by quantity. For 100 units at $45 x 80% plus $250 fixed, total is $3,850 and per-unit is $38.50.
What does the capture factor represent here? It scales the nominal rate for yield and process efficiency. At 80% capture, the effective assembly value applied is 80% of the raw rate, reflecting that not every hour or part converts cleanly into a shippable unit.
Why is per-unit cost lower than the raw rate in the example? Because the 80% capture factor pulls the $45 rate down to $36 of captured value per unit, and only the $250 fixed cost adds back, netting $38.50 per unit across 100 units.
How does batch size change per-unit cost? Fixed cost is spread over more units as quantity rises, so per-unit cost falls. The same $250 setup adds $2.50/unit at 100 units but $25/unit at just 10 units.
Should overhead go in the rate or the fixed cost? Put variable overhead that scales with each unit into the rate, and one-time setup, fixturing and programming into fixed cost, so batch-size effects come out correctly.

Last reviewed 2026-05-12.