Manufacturing calculators that show their working
Free, no-signup calculators for the numbers a shop floor actually runs on: OEE, takt time, capacity, scrap, machine cost and inventory. Every page gives you the formula, a worked example and the assumptions behind it, so the result holds up when someone asks you where it came from.
Measure how much of your available time actually turns into good parts. These are the metrics that tell you whether a line is constrained by time, speed or quality.
OEE Calculator
Overall Equipment Effectiveness with a full time-loss breakdown.
Takt Time Calculator
How often you must finish one unit to meet customer demand.
Cycle Time Calculator
Convert a timed observation into seconds per unit and units per hour.
Production Capacity Calculator
Turn cycle time and available hours into realistic capacity.
Scrap Rate Calculator
Scrap, rework, first pass yield and the cost of what you throw away.
Turn equipment and labour inputs into a defensible cost per hour and cost per unit, including the depreciation and burden most quick estimates leave out.
Size order quantities and buffers with the standard formulas, so the answer you bring to a planning meeting is reproducible instead of a gut feel.
Why these calculators exist
Most manufacturing formulas are not complicated — OEE is three ratios multiplied together, takt time is a division. What goes wrong is rarely the arithmetic. It is the definitions: whether changeover counts as downtime, whether the denominator is planned time or shift length, whether the ideal cycle time came from the machine specification or from the best run anyone remembers.
Each page here states its definitions explicitly, works through a realistic example with the numbers visible, and lists what the calculation deliberately leaves out. If your plant defines a term differently, you will be able to see exactly where the two answers diverge — which is usually more useful than the answer itself.
What this site is not
These are estimation tools, not an ERP or MES. They do not connect to your plant data, they do not store anything you type, and they will not replace a proper measurement programme. Use them to sanity-check a number before a meeting, to size an order, or to work out quickly whether a target is even arithmetically reachable.