Lean Six Sigma toolkit
Five free calculators for the numbers a Lean or Six Sigma project runs on. Each one shows its arithmetic, and each one says how far its answer can be trusted, because a capability index or a sigma level from a small sample is a range, not a number.
Nothing you type into them leaves your browser. They count visits, like every page on this site, but never what you enter.
The tools, in the order to use them
- Control Chart Maker
I-MR, c and p charts with the four Western Electric run rules. - Process Capability Calculator
Cpk with its confidence interval, a Cpk against Ppk drift check and a normality test. - Sigma Level Calculator
DPMO and sigma level with the 95% interval, and whether a kaizen really cut defects. - Takt Time and Line Balance Calculator
Takt time, line balance and the bottleneck, with stations that miss takt on slow cycles. - OEE Calculator
OEE with each loss in minutes, and the one fix worth most.
Why this order
Check the process is stable before you measure it. A control chart comes first because capability and sigma level describe a process that behaves the same way from day to day. If the chart shows signals, a Cpk or a sigma level from that data describes neither the process before the change nor the one after it.
Then measure how well it meets the requirement. Process capability works on measurements against a specification; the sigma level works on defect counts. Use whichever your process produces.
Then look at flow and losses. Takt time and line balance show whether the line can keep pace with demand, and OEE shows where a machine's time goes. Both are about time rather than defects, and both are only as honest as the cycle times you give them.
Practise it first
Bottleneck Burger is a free idle game that puts takt time, line balance and the theory of constraints on a burger line you run yourself, with the eight wastes and 6S along the way. It is a simplified model, built to make the ideas visible before you bring them to your own numbers here.