# Differences Between PPM Scrap Ratio and Scrape Rate?

Six Sigma – iSixSigma Forums General Forums Tools & Templates Differences Between PPM Scrap Ratio and Scrape Rate?

This topic contains 3 replies, has 2 voices, and was last updated by  Chris Seider 9 months, 3 weeks ago.

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• #55944

Can you please explain for me what are the differences between PPM scare% and scrape rate and how to calculate them and when i need to use each one !?

#202297

Chris Seider
Participant

PPM stands for parts per million. 1% for example is 100,000 defective per 1 million produced.

PPM or % are equivalent. Maybe I’m missing something.

#202298

thank you
may i ask you how to calculate PPM for a machine
i divide defect/yield *1000000
or defect/(defect+yield) *1000000 !? ?

#202299

Chris Seider
Participant

a typical yield is defined as [1 – (defective/(total produced))]*100%

therefore defective % is (# defective/total produced)*100 or alternatively (defective quantity/(defective quantity + good quantity)

Careful about which yield you use…if the’re a rework loop you can get a mismeasure of good quantity. This is a first pass yield question.

anyways–assuming NO rework–see the help above for defective%

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