SUPPLIER PPM CALCULATOR
You just took a reject. Does it cost you the scorecard target?
This is a parts per million defect calculator built for the twenty minutes after a customer rejection lands, when someone has to answer whether the PPM target is still reachable this period. It shows the arithmetic line by line, isolates what that one reject did to the number, and gives you a straight answer for the basis your customer actually scores you on: year-to-date, or rolling twelve months. Those two produce different answers from the same rejects, and getting them the wrong way round is how a recovery date gets committed and then missed.
Read this before you trust the answer. PLI Sorting sells containment, sorting and inspection, and this page ends with a button that asks you to call us. We therefore have a commercial interest in you concluding that a reject is expensive and that a crew on the dock is the answer. So the tool is built to be checked rather than believed: every division is on screen, every formula is written out in plain language further down, nothing is gated behind an email, and the arithmetic runs entirely in your browser.
It is also built to say no. Sorting and containment cannot change a PPM figure that is already recorded — rejected pieces stay in the numerator whatever we do afterwards — and on a rolling twelve-month scorecard nothing you buy from us moves the number before the incident month leaves the window. The worked example below is a case where the honest recommendation is to spend nothing with us at all, with the arithmetic in full.
RUN THE NUMBERS.
It is already calculated below, on a worked example. Change any figure and the answer, the arithmetic behind it and the month-by-month projection all move with it. Nothing is sent anywhere and nothing is stored.
YOUR NUMBERS
Seven figures and, on the rolling basis, a twelve-month grid.
Every value below is a worked example, not your data. Replace them with your own shipping and scorecard figures before you quote anything from this page.
Every rejected piece in the count for this period, not just the latest event.
Used directly on this basis: PPM is these two figures and nothing else.
Part of the rejected total above. Used only to show what this one event did to the number, and only on the year-to-date basis — on the rolling basis the incident month is read from the grid instead. Editable estimate
Zero is accepted. Aspirational zero-PPM targets are common and the tool handles them honestly rather than dividing by zero.
Pieces you expect to ship each month from here. Editable estimate
Closes left before the scorecard is scored. Editable estimate
Sets the pessimistic end of every band on this page. The default is a placeholder, not a prediction: replace it with your own process history, or with the defect rate PLI measured on your last containment or sorting job, which is real data from your parts rather than an assumption. Editable estimate
THE ANSWER
Calculated on load and again on every keystroke. No button to press, nothing gated.
This calculator runs in your browser and needs JavaScript. If this line is still here, the script did not load — call 216.440.6060 and a PLI quality lead will run the numbers with you.
The arithmetic is out of road for this period. What to do with the customer instead
Check these entries
The arithmetic
- Pieces shipped
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- Rejected pieces
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- PPM —
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- PPM before this reject event —
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- What this one reject did
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- Customer target
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- Distance from target
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Recovery on the accumulating basis
- Clean pieces still to ship —
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- Months at your forward volume, zero further rejects
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- Months at your assumed forward defect rate
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- Months you actually have
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- Pieces shipped by period close
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- PPM at period close
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Two figures, never one. The low end assumes nothing else comes back between now and the close; the high end runs your assumed forward defect rate. The real number sits in the band, and committing the low end to a customer is how a recovery date gets missed in writing.
Roll-off on the rolling 12-month basis
Pieces to ship to recover: not shown on this basis, deliberately. A fixed-length window drops a month off the back for every month it adds, so at flat volume the denominator does not grow and clean shipments dilute nothing. There is no quantity that fixes this. There is a date.
- Largest reject month in the window
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- Rejects sitting in that month
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- That month leaves the window at the
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- Which is
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- Month the step-down is waiting on Not always the largest one: two reject months and the newer one is what holds the number up.
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- First window at or below target
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- Which is
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- Window PPM at your period close
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Which basis this is, and why the answers differ
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Month by month
| Reporting close | Shipped | Rejects | PPM · no further rejects | PPM · at assumed rate | Status |
|---|
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Planning arithmetic only. This page is not a release, disposition or deviation authority, and nothing it prints clears product to ship. Disposition stays with your quality organisation and your customer.
THE ONE MISTAKE
THAT GETS CORRECTED.
Both bases are called PPM. They are not the same calculation, and only one of them can be recovered by shipping.
On a year-to-date or quarter basis the denominator accumulates. Every clean piece you ship is added to it and the same rejects are spread across a larger number, so the parts per million figure genuinely falls month by month. Asking “how many clean pieces to get back to fifty” is a fair question with a real answer, and this calculator gives it.
On a rolling twelve-month basis the window is a fixed length. Every month it takes on drops one off the back, so at flat volume the denominator stays roughly where it is. Nothing dilutes. The supplier scorecard PPM figure holds almost flat for months and then steps down sharply, in one move, when the month carrying the reject finally leaves the window.
The failure mode is applying the first formula to the second situation. It returns a recovery date months early because it assumes a denominator that keeps growing when the real one does not. That number gets promised in a supplier review, the window does not move, and the credibility spent on it does not come back. So on the rolling basis this tool refuses to print a pieces-to-ship figure at all. It shows you what the wrong formula would have said, labelled as such, next to the date the window actually clears.
If you do not know which basis your customer scores you on, that is the first thing to go and find out. It is usually written into the supplier quality manual or printed on the scorecard itself, and it changes the answer more than any other input on this page.
HOW THIS IS CALCULATED.
Five formulas, in plain language. Check them against your own scorecard before you rely on anything here.
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How to calculate PPM defects
PPM = (rejected pieces ÷ pieces shipped) × 1,000,000Parts per million is a rate, not a count. Sixty-two rejected pieces out of 480,000 shipped is 129.2 PPM. The multiplication by a million is only a change of units, so that small numbers stay readable. A defect rate of 0.0000129 and 12.9 PPM are the same number wearing different clothes.
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Clean pieces to reach the target — accumulating basis only
X = (rejected pieces × 1,000,000 ÷ target PPM) − pieces already shippedSolve the PPM equation for the shipped quantity that would put you on the target, then subtract what you have already shipped. Divide the remainder by your monthly volume and round up, and that is the number of months. This is valid only where the denominator accumulates. Applied to a rolling window it overstates recovery.
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Rolling twelve months
PPM = (rejects across the trailing 12 months ÷ pieces shipped across the trailing 12 months) × 1,000,000Each new month added drops one off the back. At flat volume the denominator is roughly constant, so PPM does not decay with future clean shipments: it holds and then steps down when the month carrying the rejects leaves the window. The answer on this basis is a roll-off date. A month sitting n positions from the oldest end leaves after n further closes.
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The band, and why there is never one number
low end: no further rejects · high end: your assumed forward defect rateAny projection depends on what happens next, which nobody knows. Every forward-looking figure here is therefore given as a range: the optimistic end assumes zero further rejects, the pessimistic end runs the forward defect rate you entered. Where the two ends fall on opposite sides of the target, the honest answer to the customer is “it depends on the next four months,” not a date.
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What happens at the edges
target 0 PPM · zero shipped · zero forward volume · blank fieldsA target of zero is common and is handled rather than divided by: once a reject is on the books, dilution moves PPM towards zero but never reaches it, so the tool says the period is scored above target instead of returning infinity. Nothing shipped means there is no rate to report. No forward volume means nothing dilutes. Blank or negative entries are clamped to zero and listed back to you above the answer, rather than quietly becoming a number you did not type.
THE CASE WHERE
WE TELL YOU NOT TO BUY.
A PPM calculator published by a sorting company is worth nothing if it never says “this is not a sorting problem.” Here is one, with the arithmetic in full. Every figure below is reproducible in the calculator above.
Rolling twelve-month scorecard, flat 60,000 pieces a month, so 720,000 in the window. Eleven of those months carry six rejected pieces between them. The twelfth — the month that just closed — carries 54 from a single containment-scale escape. The customer target is 50 PPM and the scorecard period closes in five months.
The window reads 60 ÷ 720,000 × 1,000,000 = 83.3 PPM. Before the escape it read 6 ÷ 720,000 × 1,000,000 = 8.3 PPM. One event moved this supplier 75 PPM in a month.
Apply the accumulating formula and it asks for (60 × 1,000,000 ÷ 50) − 720,000 = 480,000 clean pieces, which is eight months at 60,000. That is the number that gets promised in a supplier review. It is wrong. The denominator is not growing: every month this window adds 60,000 pieces it drops 60,000 off the back, so at the eighth close the scorecard still reads 76.4 PPM and the commitment is publicly missed.
The window clears at the twelfth close, when the escape month leaves it, and not before. The period closes at the fifth, with the scorecard at 79.2 PPM against a 50 PPM target. This period is gone, and no purchase changes that.
So here is what we would actually say if you called us with these numbers. Two PLI inspectors on your dock for the remaining five months is roughly 1,736 hours at a $38 loaded rate: about $66,000. Run that spend through this page and the improvement to this period's scorecard PPM is 0.0. Sorting cannot retract a piece the customer has already rejected; those 54 pieces sit in the numerator until the month rolls off, whatever we do on your dock afterwards.
If your root cause is closed and verified, buy nothing from us. Take the roll-off date to your customer, show them the window, and spend the five months on the eight-D. Containment from us is worth its price here for one reason only — stopping a second escape from landing in month 13 and resetting the twelve-month clock — and if you are already confident that will not happen, that is a job we should not be quoting.
The arithmetic
| Reporting close | Window shipped | Window rejects | Window PPM |
|---|---|---|---|
| Today | 720,000 | 60 | 83.3 |
| 5th close — period close | 720,000 | 57 | 79.2 |
| 8th close — what the wrong formula promised | 720,000 | 55 | 76.4 |
| 11th close | 720,000 | 54 | 75.0 |
| 12th close — the escape month leaves | 720,000 | 0 | 0.0 |
Read the shipped column first. It does not move, and that is the entire argument. The rejects column is the only thing that changes, and it only changes when a month carrying rejects leaves the window.
Reproduce it above: choose the rolling 12-month basis, set every month's shipped to 60,000, put 54 rejects in the newest row, and spread six rejects across the other eleven. Target 50, five months remaining.
WHEN THE PERIOD
IS ALREADY LOST.
The calculator will tell you plainly when the target cannot be reached. That is not the end of the conversation, and the number is not the only thing being scored.
Separate the number from the status
PPM is one line on a supplier scorecard. Response time, containment quality, problem-solving discipline and communication are usually scored alongside it, and those are the lines you can still move this period. A supplier who reports the miss early, with the arithmetic attached, is treated differently from one whose customer finds it at the review.
Take the date to them before they ask
If the recovery is a roll-off rather than a dilution, say so and name the month. Show the window. Customers escalate to controlled shipping over uncertainty far more often than over a number, and a supplier who can explain exactly when their own scorecard clears is demonstrating control of the process, which is the thing actually being assessed.
Spend the period preventing the next one
Every month the window holds flat is a month one more escape would reset the clock on. That is where containment, 100 percent inspection at the customer or your own dock, and a clean break between suspect and verified stock earn their cost — not by fixing this period's number, but by protecting the roll-off you have already committed to.
QUESTIONS.
What is a good supplier PPM target?
It is set by your customer, not by an industry rule. Automotive targets commonly sit between zero and fifty PPM on production parts, with safety and appearance characteristics often scored separately and tighter. Use the number written on your scorecard rather than a benchmark, because the scorecard is what you will be measured against.
Why does my PPM not move even though we have shipped clean for months?
Almost always because the scorecard is on a rolling twelve-month window. The denominator is not growing, so clean shipments have nothing to dilute. The number will hold roughly flat until the month carrying the rejects leaves the window, then step down in one move. Switch the basis toggle above to see the date.
Does a sort or containment activity change the PPM already recorded?
Not retrospectively. Pieces already rejected by the customer stay in the numerator. What containment changes is everything after it: it stops further escapes reaching the customer, which is what protects the roll-off date this calculator gives you. Whether any specific rejection is credited back is a matter for your customer, not for arithmetic.
Is this calculator a release or disposition authority?
No. It is a planning tool. It does not clear product, authorise a deviation, or substitute for your quality management system. Disposition stays with your quality organisation and your customer.
Do you keep the numbers I type in?
No. The calculation runs entirely in your browser. Nothing is sent to a server, nothing is stored, and there is no email gate on the result.
Why should I trust a PPM calculator published by a sorting company?
Because a tool that always recommends the seller is worth nothing to the buyer, and supplier quality engineers check arithmetic for a living. PLI Sorting sells containment, sorting and inspection, so we have put every division on screen, written out every formula in plain language, refused to print a pieces-to-ship figure on the basis where it would flatter us, and published a worked example in which the honest recommendation is to spend nothing with us at all. If our quote and this page disagree, bring us the page.
THE NUMBER IS ONE THING.
THE NEXT REJECT IS THE REAL ONE.
PLI Sorting contains quality spills, sorts good from bad, and gives you documented, independent results your customer will accept. If this page just told you the period is not recoverable, the work now is making sure the roll-off is not reset by another escape.
sales@phillipslightindustrial.com
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