What Is Rolled Throughput Yield? Definition and Uses

Rolled throughput yield, or RTY, is the probability that a unit passes through every step of a process defect-free the first time — no rework and no scrap anywhere along the way. It is calculated by multiplying the first pass yield of every step. That multiplication is the point: a process built from individually respectable steps can still deliver a poor overall yield, and RTY is the metric that refuses to hide it.

How it works

Take the first pass yield of each process step — the fraction of units that clear that step correctly without rework — and multiply them together. Because every factor is less than one, the product only falls. Five steps at 95 percent each yield roughly 77 percent rolled throughput: nearly a quarter of units need rework or scrapping somewhere, even though every individual step looks fine on its own dashboard.

Contrast this with final yield, which counts whatever eventually ships as good — including everything fixed along the way. Final yield can read 99 percent while the process quietly pays for a hidden factory of inspection and rework. RTY exposes the difference, and it tells you where to dig: the step with the lowest first pass yield is dragging the product down hardest. It is also why short processes flatter and long ones humble — every added step is another factor below one.

A worked example

An illustrative case: an electronics assembler builds control panels in four steps. First pass yields: board assembly 96 percent, soldering 92 percent, firmware load 99 percent, final test 95 percent. Multiply: 0.96 × 0.92 × 0.99 × 0.95 gives roughly 0.83 — about 83 percent of panels flow through untouched, though no single step looks alarming. Soldering, the lowest factor, becomes the improvement target. Lifting it to 97 percent would move rolled throughput to about 88 percent — a case the team can make in one line of arithmetic.

• Measure first pass yield honestly at each step — RTY inherits every flattery in its inputs
• Count rework as failure even when the reworked unit ships fine
• Use RTY to rank steps for improvement, not to shame the teams running them
• Expect low numbers at first; long processes multiply mercilessly
• Track RTY over time — a rising product of yields is clean evidence a process is truly healing

A chain of good steps can still make a poor process — multiplication is unforgiving.

Rolled throughput yield is a Measure-phase staple of our Green Belt program ($299, about 35 hours, with a 100-question proctored exam), and Black Belt ($499, about 60 hours) builds on it, connecting yield mathematics to sigma levels and process capability. Once you have computed RTY for a process you know, final yield never looks quite trustworthy again.