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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.ComparisonFIFO vs LIFO: What Actually Changes, and What Does NotFIFO and LIFO are assumptions about which cost you attach to a sale, not about which box leaves the warehouse. Worked through identical purchases and sales, they move cost of sales, inventory, profit and tax — but operating cash before tax is identical to the cent.ExplainerThe Cash Conversion Cycle: the Number That Explains Why You Are Out of CashCCC = DIO + DSO − DPO. It is the number of days your cash is out of your hands, and it is the reason a profitable, growing business runs out of money. Worked end to end, with the negative-cycle case that makes suppliers your cheapest lender.ComparisonCurrent Ratio vs Quick Ratio, and What Neither Tells YouThe quick ratio removes inventory because inventory is the current asset that may not convert. Two companies with an identical current ratio can be five times apart on the quick ratio — and both measures are still blind to the one thing that actually stops a company paying: timing.ExplainerReturn on Assets: What the Ratio Says About a Business, and What It HidesReturn on assets, return on net assets and return on capital employed are one family with two moving parts. On the same balance sheet they read 8.3%, 10.2% and 15.6% — and the two steps between them are exactly the two decisions you are making.