Can I compare kilograms with pounds?

No, convert both masses to pounds before entry. The calculator uses one explicit mass basis and does not apply an adjustable conversion multiplier.

Is all removed mass scrap?

No, the difference can include reusable offcuts as well as chips. Record their recovery value separately when comparing total costs.

Can a ratio below one be valid?

Not for this subtractive scope. Added coatings, inserts or deposited material require a different mass boundary before comparing purchased and finished mass.

Does a lower ratio prove a cheaper process?

No, machining time, tooling, qualification and purchased stock price can change independently. Use this ratio as one input to the process comparison.

Aerospace & Defense Manufacturing calculator

Buy-To-Fly Ratio Calculator

Compare purchased stock with the mass retained in a finished flight part. Enter both masses in pounds for the same part and manufacturing scope.

What this calculator does

Compare purchased stock mass with the finished flight part from the same manufacturing scope.

Formula used

Buy-to-fly ratio = purchased mass ÷ finished mass
Material utilization (%) = finished mass ÷ purchased mass × 100
Material outside finished part = purchased mass − finished mass

Inputs explained

Purchased Stock Mass: Purchased stock assigned to this part, including cutoff and gripping allowances.
Finished Part Mass: Released drawing or measured mass of the corresponding finished part.

How to use the result

Best suited to stock form Comparison, material utilization review.
Material outside the part includes reusable offcuts and machining chips. The ratio excludes machining cost, material certification cost and scrap credit. Finished mass below 0.000001 lb is outside the supported numerical range.

Current U.S. benchmarks

Steel mill PPI stands at 381.162 (BLS, Aug 2026), up 23.4% from a year earlier. New factory orders are up 8.5% year over year (Census).
The U.S. has 11,691 transportation equipment establishments employing about 1,682,910 workers (Census County Business Patterns, 2023).

Common questions

Can I compare kilograms with pounds? No, convert both masses to pounds before entry. The calculator uses one explicit mass basis and does not apply an adjustable conversion multiplier.
Is all removed mass scrap? No, the difference can include reusable offcuts as well as chips. Record their recovery value separately when comparing total costs.
Can a ratio below one be valid? Not for this subtractive scope. Added coatings, inserts or deposited material require a different mass boundary before comparing purchased and finished mass.
Does a lower ratio prove a cheaper process? No, machining time, tooling, qualification and purchased stock price can change independently. Use this ratio as one input to the process comparison.

Last reviewed 2026-10-06.