Cost and Quoting

What Drives Cost Per Unit in Lean Operations and How to Quote It

A money-focused breakdown of the cost drivers behind a lean production quote, how to load overhead honestly, and the estimating errors that quietly erase margin.

Cost per unit in a lean operation splits into four buckets: direct material, direct labor, machine time, and allocated overhead, with scrap layered on top of the first three. On a typical machined part, material might be 8.50 dollars, labor 3.20, machine time 6.40, and overhead 4.90, giving a loaded cost near 23 dollars before scrap. The mistake is treating these as fixed. Labor and machine cost per unit fall as batch size rises because setup amortizes across more pieces, so the same part can swing from 27 dollars at a batch of 100 to 21 dollars at a batch of 1,000.

Setup is the driver estimators underprice most often. A 90-minute changeover at a 55-dollar loaded labor rate plus 32 dollars per machine hour of idle spindle costs about 130 dollars every time you run the job. Spread across 100 units that is 1.30 dollars per piece; across 2,000 units it is 6.5 cents. The Unit Cost and Batch Size calculators together show where the curve flattens. If a customer wants small, frequent releases, price the setup into each release rather than assuming one annual setup, or you will eat the difference on every short run.

Labor cost needs the loaded rate, not the wage. A 22-dollar wage carries payroll tax, benefits, and paid time off that push the fully burdened rate to roughly 33 to 38 dollars per hour, a 50 to 70 percent uplift. The Labor Cost calculator applies that burden and multiplies by the standard time per unit. Quote against demonstrated cycle time, not the engineered standard: if the router says 45 seconds but the floor runs 58 with a realistic efficiency of 78 percent, you are 29 percent short on every labor line and it compounds across thousands of units.

Machine time is priced through the machine hour rate, which folds depreciation, power, maintenance, tooling, and floor space into one number, often 28 to 65 dollars per hour depending on the asset. Use the Machine Hour Rate calculator to build it, then apply it to spindle-on time only. A subtle leak: paying the full rate for setup and teardown minutes when the machine is not producing. Track those minutes and bill them explicitly as setup rather than smearing them into the per-unit rate, so a slow-changeover job does not silently subsidize a fast one.

Scrap and rework quietly delete margin. If your first-pass yield is 94 percent, you must start 106.4 units to ship 100, so every good unit carries 6.4 percent extra material, labor, and machine cost. On a 23-dollar loaded part that adds about 1.47 dollars, and rework labor on the salvageable rejects adds more. Estimate scrap from actual yield history by part family, not a single plant-wide number, because a tight-tolerance job may run 88 percent yield while a simple bracket runs 99. Quoting both at 96 percent overprices one and underprices the other.

Overhead allocation decides whether the quote holds up under scrutiny. Rather than a flat percentage markup, tie overhead to a cost driver such as machine hours or labor hours. If plant overhead is 1.8 million dollars against 60,000 machine hours, the rate is 30 dollars per machine hour, applied by how long the part actually occupies the machine. A part using 0.11 machine hours absorbs 3.30 dollars of overhead, defensibly. Flat markups overcharge low-machine, high-labor parts and undercharge machine-hungry ones, which is exactly how you win the wrong jobs and lose the profitable ones.

Convert loaded cost into a price with a margin, not a markup, and know the difference. A 23-dollar cost at a 30 percent margin prices at 23 divided by 0.70, or 32.86 dollars, whereas a 30 percent markup only reaches 29.90 and leaves you at a 23 percent margin. The Quote Margin calculator handles the conversion so you do not confuse the two. Also check the Break-Even Quantity: if fixed tooling and setup total 4,000 dollars and contribution per unit is 9.86, you break even at 406 units, which tells you whether a small order is even worth quoting.

Estimates go wrong in predictable places, so audit them before they ship. Confirm the batch assumption matches the actual release pattern, since a quote built on 2,000-unit runs collapses if the customer orders 150 at a time. Verify the burdened labor rate, the productive machine hours behind the machine rate, and the yield by part family. Add a contingency line for material price volatility, because a 12 percent steel move on an 8.50-dollar material cost adds a dollar per unit. A defensible quote lists every driver with its source, so when the customer pushes back you defend line by line instead of discounting blind.

Published 2026-07-01.