PlantCalc

About PlantCalc

A small, deliberately narrow reference site for manufacturing and production calculations.

What this site is

PlantCalc publishes 10 calculators covering performance measurement, unit cost and inventory planning — the arithmetic that production, industrial engineering and supply planning teams use every day. Each calculator is a single page with a live form, the formula it implements, a worked example with the intermediate figures shown, a list of what the calculation leaves out, and answers to the questions people actually ask about the metric.

Everything runs in your browser. No numbers you type are transmitted, stored or logged, and there is no account to create.

How the pages are built

The formulas follow standard industrial engineering practice: OEE as the product of availability, performance and quality; takt time as available time over demand; EOQ from the Harris economic order quantity model; safety stock by the max-max method. Where a term has more than one accepted definition — most notably what counts as planned downtime in OEE — the page states which one it uses rather than silently picking one.

Every calculation is covered by test cases that check the published example figures. If a formula changes, the page's own worked example has to change with it, which makes it hard for a quiet error to survive a revision.

What this site is not

It is not a substitute for your own process data, and it is not a planning system. The outputs are estimates built from the inputs you supply; if an input is wrong, the answer is wrong in exactly the same proportion. For commercial commitments — quotations, capacity promises, inventory investment decisions — verify against measured data first.

Corrections

If a formula is wrong, a definition is misstated, or an example does not add up, that is a bug and it will be treated as one. Write to contact@plantcalc.pages.dev with the page address and the figure you believe is wrong.

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