Engineering Unit Converter

What this tool does

Converts the units that actually turn up on structural work: length and area, force and mass, stress and pressure, moment, volume and temperature, both directions between imperial and metric.

It shares a page with the scientific calculator, so a conversion and the arithmetic that follows it happen in the same place.

Formula

The conversions worth knowing by heart on a steel job.

Assumptions

Conversions are exact factors where the definition is exact and rounded published factors otherwise. Nothing here knows what a quantity means; it converts the number you give it.

• Gauge against absolute, pressure conversions are of magnitude only. Whether a figure is gauge or absolute travels with the drawing, not with the number.
• Display rounding, results are rounded for display; the full-precision value is what carries into the next conversion.

Worked example

Applications

• Imported drawings, read a metric detail against an imperial shape table without re-deriving it each time.
• Mill certificates, check a metric MTR against the imperial grade a drawing calls out.
• Equipment data, convert a supplier's kN or kg rating into the kip and lb a lift plan is written in.

Field notes

• The US short ton (2,000 lb), the metric tonne (2,205 lb) and the long ton (2,240 lb) are three different numbers. On an international order, say which.
• Convert once, at the end. Rounding at every step is how an untraceable error creeps into a number.
• Metric ASTM designations (A992M, A572M) already carry the rounded SI values. Use those rather than converting the imperial ones yourself.