Cost Estimation

Aerospace and Defense Cost Estimation: Building a Defensible Quote

A practical breakdown of aerospace and defense cost per unit, from material burn and certification to inspection labor, small-lot overhead, and where quotes go wrong.

In aerospace machining, material is the line item that sinks quotes because you pay for metal you turn into chips. At a buy-to-fly ratio of 8:1, a part that finishes at 6 lb consumes 48 lb of stock. Ti-6Al-4V bar at 22 dollars per pound puts raw material at roughly 1,056 dollars per part, and even after crediting titanium chip scrap at 3 to 5 dollars per pound you recover only about 170 dollars. Estimators who quote off finished weight instead of stock weight understate material by five to eight times. Use the Buy-to-Fly Ratio calculator to fix stock mass before you price anything.

Certification and traceability are real dollars, not overhead you can wave away. Full material certification with chemical and mechanical test reports, DFARS-compliant melt-source documentation, and heat-lot traceability commonly adds 150 to 600 dollars per lot in labor and testing. Because it is a per-lot cost, it detonates on small defense orders. A 40 dollar traceability package is 40 dollars per unit on a lot of one and 80 cents on a lot of fifty. The Material Certification Cost and Traceability Cost per Lot calculators let you carry these as explicit lot charges rather than burying them in a fuzzy overhead percentage.

Inspection labor is often the second largest cost after material and is routinely under-quoted. If inspection burden runs 20 percent, then every 40 hours of machining carries 10 hours of inspection labor. At a loaded quality-labor rate of 95 dollars per hour, that is 950 dollars per unit of inspection that estimators frequently fold into a token allowance. Price first article separately: a 240 characteristic FAIR at roughly 18 measurement hours plus documentation can reach 2,500 to 4,000 dollars of nonrecurring cost that must be amortized across the order or billed as NRE.

Scrap and rework must be priced as expected cost, not hoped away. Expected scrap cost equals part cost times scrap rate divided by one minus scrap rate, because scrapped units still consumed material and machine time. At a 6 percent scrap rate on a 1,400 dollar part, that is 1,400 x 0.06 / 0.94, about 89 dollars per good unit shipped. Add rework at, say, 2 hours per reworked unit times a 4 percent rework rate times a 110 dollar shop rate, another 8.80 dollars per unit. The Supplier Escape Cost calculator quantifies the far larger downstream hit when a defect ships and gets caught at the customer.

Overhead behaves differently at aerospace volumes because runs are small and setups dominate. A 6 hour setup amortized over a lot of 8 adds 0.75 setup hours per unit; over a lot of 200 it adds 0.03. AS9100 compliance, calibration, and audit readiness load your shop rate: the AS9100 Audit Load calculator helps translate audit and surveillance hours into a per-hour burden, which for certified aerospace shops often adds 8 to 15 dollars per direct labor hour on top of machine and facility overhead. Ignoring lot size when spreading setup and quality overhead is the most common quoting error.

Build the quote as a stack so it survives customer scrutiny: stock material minus scrap credit, machine hours times machine rate, direct labor times loaded rate, inspection and FAI labor, per-lot certification and traceability, expected scrap and rework, then overhead, then margin. For a representative titanium detail part you might see 890 dollars material, 620 dollars machining, 310 dollars labor, 480 dollars inspection, 95 dollars traceability, 130 dollars scrap and rework, and 340 dollars overhead, a 2,865 dollar cost base. A line-item quote wins disputes; a single number invites a customer teardown you will lose.

Defense work adds margin rules civilian quoting ignores. On negotiated contracts, allowable profit is scrutinized and weighted-guidelines margins often land between 8 and 15 percent, far below commercial machining targets of 25 to 35 percent. The Defense Contract Margin calculator helps you model target profit against cost base and contract type. The estimating failure mode is assuming commercial margin on a cost-plus or fixed-price defense job, then discovering the fee is capped. Price the compliance cost, then set fee to the contract vehicle, not to your commercial habit.

The biggest estimating misses are structural, not arithmetic. Quoting off finished weight, treating certification as free, using a blanket 10 percent inspection allowance, and applying commercial margin to defense fee together can understate a quote by 30 to 60 percent. The escape cost of one defective unit reaching a prime, including containment, source inspection, and corrective action, routinely runs 5,000 to 50,000 dollars, dwarfing the 89 dollar scrap allowance. Quote the true cost of quality up front; the shops that lose money are the ones that treat conformance as an afterthought line rather than a priced deliverable.

Published 2026-07-01.