# Lot Rejection Rate, PPM and Sigma Level Calculator

> Source: https://netray.co/tools/sap-qm-lot-rejection-ppm-sigma-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

Convert lots inspected, lots rejected and defective units into rejection rate, PPM, DPMO and sigma level.

## Category

quality

## Erp

SAP S/4HANA

## Audience

- Supplier quality
- SAP QM consultant
- Quality manager

## Tool

**Kind:** calculator

**Inputs:**

#### Lots inspected

**Key:** lots_inspected

**Type:** number

**Default:** 240

**Min:** 1

**Step:** 1

**Unit:** lots

#### Lots rejected

**Key:** lots_rejected

**Type:** number

**Default:** 6

**Min:** 0

**Step:** 1

**Unit:** lots

#### Units received

**Key:** units_received

**Type:** number

**Default:** 120000

**Min:** 1

**Step:** 1000

**Unit:** units

#### Defective units found

**Key:** units_defective

**Type:** number

**Default:** 180

**Min:** 0

**Step:** 10

**Unit:** units

#### Defect opportunities per unit

**Key:** opps

**Type:** number

**Default:** 4

**Min:** 1

**Step:** 1

**Help:** Number of independent ways a unit can be defective.

**Outputs:**

#### Lot rejection rate

**Key:** lot_rej

**Expr:** lots_rejected / lots_inspected * 100

**Format:** percent

**Primary:** true

#### Lot acceptance rate

**Key:** lot_acc

**Expr:** 100 - lot_rej

**Format:** percent

#### PPM defective

**Key:** ppm

**Expr:** units_defective / units_received * 1000000

**Format:** integer

**Primary:** true

#### DPMO

**Key:** dpmo

**Expr:** units_defective / (units_received * opps) * 1000000

**Format:** integer

#### Unit yield

**Key:** yield_pct

**Expr:** 100 - ppm / 10000

**Format:** percent

#### Sigma level (with 1.5 shift)

**Key:** sigma

**Expr:** normsinv(1 - clamp(dpmo, 1, 999999) / 1000000) + 1.5

**Format:** decimal

**Chart:**

#### Sigma level vs defective units found

**Type:** line

**X:** units_defective

**From:** 10

**To:** 1000

**Steps:** 30

**Series:**

- sigma

**Disclaimer:** Sigma level uses the conventional 1.5 sigma long-term shift. Quote the method when reporting to customers.

## Content

**Intro:** Supplier scorecards live on three numbers: how many lots you reject, how many parts per million are bad, and what that means in sigma terms. This calculator turns raw counts from SAP QM usage decisions into all three.

**Sections:**

#### How to use it

**Body:** Enter lots inspected and lots rejected for the period, the units received and the defective units found, and the number of defect opportunities per unit. PPM measures defective units, while DPMO measures individual defects per opportunity, so the opportunities field only affects DPMO and sigma. Use one opportunity per unit if you want a simple pass or fail view.

#### Formulas

**Body:** Lot rejection rate = rejected lots / inspected lots. PPM = defective units / units received x 1,000,000. DPMO = defects / (units x opportunities) x 1,000,000. Sigma level = normsinv(1 - DPMO/1,000,000) + 1.5, where the 1.5 is the Motorola long-term shift convention. Three sigma is roughly 66,800 DPMO and six sigma 3.4 DPMO.

#### Where the counts come from

**Body:** In SAP QM, inspection lots end with a usage decision (QA11), and the quality score and lot statistics sit in the vendor evaluation and the QM information system. Make sure your counts match one definition of rejection: lots with a rejected usage decision, or lots with blocked stock posted, since they can differ when conditional acceptance is used.

#### Common mistakes

**Body:** Counting lots accepted on deviation as good without saying so, comparing PPM across suppliers with different sampling plans, and calculating PPM from sample defects without scaling to the lot. Where only samples are inspected, PPM from samples estimates but does not measure lot quality.

**Cta:** We can calculate vendor PPM and rejection trends from SAP QM data on demand and highlight the vendors drifting, using your own system.

**Faq:**

#### What is the difference between PPM and DPMO?

**Answer:** PPM counts defective units per million units. DPMO counts defects per million opportunities, so a unit with two defects counts twice and the number of ways to fail is part of the denominator.

#### Why add 1.5 to the sigma level?

**Answer:** It is a convention that allows for long-term drift of the mean. Without the shift, the same DPMO would give a sigma level 1.5 lower.

#### What is a good supplier PPM?

**Answer:** It depends on the industry and part. Automotive customers often target double digit PPM, while commodity items may accept hundreds. Set targets in the quality agreement.

#### Can I use sample defects?

**Answer:** Only if the sample is random and you scale it up. Otherwise the result describes the sample, not the lot population.

## Search terms

ppm calculator defects, dpmo calculator, sigma level calculator, lot rejection rate calculator, supplier ppm calculation, defects per million opportunities, vendor quality ppm SAP QM

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