Methodology

Formula sources

The calculators use standard mechanical and electrical engineering formulas and relationships commonly presented in engineering textbooks and public standards. The How it works section on each tool page states the formula used and gives a numerical example.

These are general engineering relationships. Their use here does not imply certification or approval by a manufacturer or standards organization.

Unit conventions

Every tool explicitly labels its input and output units, such as mm, N·m, bar, A, and Ω/km. Enter values in the units shown beside the fields. Where a tool offers a unit choice, the selected unit determines how the value is interpreted.

Conversion pages identify conventions that can otherwise be ambiguous, including US gallons for GPM and the International Table definition for BTU (IT).

Precision and rounding

Results are generally displayed to two decimal places. Some tools show additional decimal places to keep small values or conversion factors useful; the displayed precision depends on the tool. Thousands separators are commas.

Calculations use unrounded intermediate values at the browser's available numerical precision. Rounding is applied when a result is displayed. Displayed decimal places do not indicate the accuracy of measurements or the suitability of the model.

Known limitations

The tools use simplified models and the assumptions stated on their pages. Ideal gear and pulley calculations ignore friction and transmission losses. Ideal cylinder forces do not include seal friction or other mechanical losses.

Electrical estimates may treat resistance, efficiency, and power factor as fixed. Real temperature rise, changing loads, and power factor variations can change the result. Models for balanced three-phase circuits or unloaded resistor dividers apply only under those stated conditions.

Check equipment documentation and actual operating conditions. Critical designs require review by a qualified engineer; see the Terms of Use.

Reporting an error

For error-reporting details, see the Contact page when it is available. Include the tool name, input values and units, the result shown, and the expected result with a formula or reference so the calculation can be checked.