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Six Sigma Process Capability Calculator (Cp, Cpk, Pp, Ppk)

Cp against Cpk is the whole point: Cp assumes the process sits centred between the limits, Cpk does not, so a process can score an excellent Cp and a dreadful Cpk simply by drifting off target. Work from summary statistics, or paste raw measurements in subgroups and get σ_within from R̄/d₂ (Cp, Cpk) alongside σ_overall (Pp, Ppk) — two different numbers that are constantly confused. Sigma level, DPMO, expected yield and a chart against the spec limits round it off; one-sided specs are supported.

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Open Six Sigma Process Capability Calculator (Cp, Cpk, Pp, Ppk) and you get an answer straight away, with no account to create. It covers Cp, Cpk — adjust any of them and the result follows immediately.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What is Six Sigma Process Capability Calculator (Cp, Cpk, Pp, Ppk)?

Cp against Cpk is the whole point: Cp assumes the process sits centred between the limits, Cpk does not, so a process can score an excellent Cp and a dreadful Cpk simply by drifting off target. Work from summary statistics, or paste raw measurements in subgroups and get σ_within from R̄/d₂ (Cp, Cpk) alongside σ_overall (Pp, Ppk) — two different numbers that are constantly confused. Sigma level, DPMO, expected yield and a chart against the spec limits round it off; one-sided specs are supported.

What does it take into account?

It factors in Cp, Cpk. Change any of them and the output follows immediately.

When would I actually use this?

Running the week: issuing an invoice or a quote, knowing what is in stock and what to reorder, and seeing whether cash covers what is due.

What is the most common mistake?

Reading profit as cash. A profitable month with sixty-day payment terms can still leave the account empty — the two numbers answer different questions.

Is there a tool for the next step?

Straight-line depreciation calculator is the closest one after this: Compute the yearly straight-line depreciation of an asset.

Where do the figures come from?

The arithmetic is exact for what you enter. Invoice content, VAT treatment and mandatory mentions are set by national rules — an invoice that computes correctly can still be non-compliant.

Further reading

All guides →
ExplainerProcess Capability: Cp, Cpk and What Six Sigma Actually ClaimsCp compares the spec width to the process spread; Cpk penalises being off-centre. A process can have an excellent Cp and still make scrap — here is the case, with defect rates computed from the normal distribution rather than read off a table.ExplainerTakt Time, Cycle Time and Lead Time Are Three Different ClocksTakt is demand, cycle time is capability, lead time is what the customer experiences. Confusing them is the most common failure in a first improvement project — and Little's Law is the bridge from one to the next.ExplainerFifty-Five Days to Get Paid on Thirty-Day Terms180,000 outstanding against 1,200,000 of annual sales is 54.75 days of collection and 6.67 turns a year. On thirty-day terms, that gap is a quarter of a million financed for free.ExplainerFifty Thousand of Working Capital, and None of It SpendableCurrent assets of 150,000 less current liabilities of 100,000 gives working capital of 50,000 and a ratio of 1.5. Whether that is comfortable depends on what the 150,000 is made of.ExplainerCost of Goods Sold Is What Left the Shelf, Not What You BoughtOpening stock 40,000, purchases 120,000, closing stock 35,000 — the cost of goods sold is 125,000, and it is larger than the purchases because the shelf gave up 5,000 of what was already there.ExplainerThe Count Says 48,200 and the Books Say 50,000A gap of 1,800 is a shrinkage rate of 3.6 %. The percentage is the number that travels; the absolute figure is the one that pays for the fix.