How do you calculate supplier defect rate?

Divide rejected parts by parts received and multiply by 100. With 12 rejects out of 2,000 parts received, the defect rate is 12 / 2,000 x 100 = 0.6 percent.

How do you convert defect rate to PPM?

Multiply the defective fraction by 1,000,000. A 0.6 percent rate equals 6,000 PPM (parts per million), the unit most supplier scorecards use for benchmarking.

What is a good supplier defect rate?

World-class suppliers run in the tens to low hundreds of PPM. The example 0.6 percent equals 6,000 PPM, which is above target here by 0.4 points and typically prompts a corrective-action conversation.

What is the gap to target?

It is the supplier's actual rate minus the agreed target rate, in percentage points. A positive gap means the supplier is worse than target; the example shows a 0.4-point gap above a 1 percent... target reference.

Should I use lots or individual parts?

Use individual parts for a defect rate; use lots for a lot-acceptance rate. Part-level gives a finer, PPM-ready number, which is what most modern supplier programs track.

Why track defect rate instead of just counting rejects?

Raw reject counts scale with volume, so a high-volume supplier always looks worse. Dividing by parts received normalizes for volume and makes suppliers directly comparable.

Quality & Metrology calculator

Supplier Defect Rate Calculator

Supplier defect rate is the percentage of received parts that fail incoming inspection, and it is the single most-watched number on a supplier scorecard. This calculator divides rejected parts by parts received to give a percent-defective figure and then shows the gap to your agreed target, so you can see at a glance whether a supplier is inside contract. Supplier quality engineers, procurement teams, and receiving inspectors use it to grade vendors, trigger corrective-action requests, and support sourcing decisions. It matters because a supplier's defect rate flows straight into your line stoppages, sorts, and escape risk — poor incoming quality is the cheapest defect to catch and the most expensive to ignore.

What this calculator does

Calculate a supplier defect rate from rejected parts and parts received, and compare it against your target defect rate.
Use it for supplier scorecards, tier reviews, and corrective action decisions on incoming quality.
It computes the percentage of received parts that were rejected and the gap in percentage points between that rate and your agreed target.

Formula used

Supplier defect rate = rejected parts ÷ parts received × 100
Gap to target = supplier defect rate - target defect rate

Inputs explained

Rejected parts from the received lot:
Total parts received from supplier:
Target (agreed) defect rate:

How to use the result

Use it at incoming inspection or on a monthly supplier scorecard to grade a vendor and decide whether a corrective-action request is warranted.
A percentage can hide sample-size effects — a 0.6 percent rate from 2,000 parts is far more reliable than the same rate from 50 parts, so always read it with the received quantity in view.

Current U.S. benchmarks

U.S. manufacturing runs at 75.6% of capacity (Federal Reserve, May 2026). New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate supplier defect rate? Divide rejected parts by parts received and multiply by 100. With 12 rejects out of 2,000 parts received, the defect rate is 12 / 2,000 x 100 = 0.6 percent.
How do you convert defect rate to PPM? Multiply the defective fraction by 1,000,000. A 0.6 percent rate equals 6,000 PPM (parts per million), the unit most supplier scorecards use for benchmarking.
What is a good supplier defect rate? World-class suppliers run in the tens to low hundreds of PPM. The example 0.6 percent equals 6,000 PPM, which is above target here by 0.4 points and typically prompts a corrective-action conversation.
What is the gap to target? It is the supplier's actual rate minus the agreed target rate, in percentage points. A positive gap means the supplier is worse than target; the example shows a 0.4-point gap above a 1 percent... target reference.
Should I use lots or individual parts? Use individual parts for a defect rate; use lots for a lot-acceptance rate. Part-level gives a finer, PPM-ready number, which is what most modern supplier programs track.

Last reviewed 2026-05-12.