Engineering Unit Converter.
Convert between every unit you'll encounter on a manufacturing drawing — length, area, volume, mass, force, pressure, torque, power, and temperature. Live two-way conversion with a full reference table.
Full reference for length
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Engineering Unit Conversion
Engineers work across metric and imperial systems daily — drawings in mm, supplier specs in inches, US customers asking for psi. A reliable converter prevents costly mistakes.
Critical Engineering Conversions
- 1 inch = 25.4 mm (exact)
- 1 mm = 0.03937 inch
- 1 lb = 0.4536 kg
- 1 kg = 2.205 lb
- 1 psi = 6.895 kPa = 0.0689 bar
- 1 MPa = 145.04 psi
- 1 Nm = 0.7376 lb·ft
- 1 HP = 0.7457 kW
- °F = (°C × 1.8) + 32
Why Unit Errors Are Catastrophic
The Mars Climate Orbiter (1999) was lost because Lockheed Martin used pound-seconds for thrust while NASA used newton-seconds. Cost: ₹275 crore mission, total loss.
Common engineering unit errors:
- Pressure units: psi vs bar vs MPa vs kPa
- Torque units: Nm vs lb·ft vs kgf·m
- Energy units: J vs cal vs BTU
- Drawing tolerance: ±0.05 mm vs ±0.05" — 25× difference!
Best Practices
- Always include units on calculations and drawings — never bare numbers.
- For multinational projects, standardize on one unit system. Mention SI units (kg, m, s, A, K, mol, cd) when in doubt.
- Cross-check critical values in two systems — catches transcription errors.
- Use parameterized templates so values can be unit-flipped without manual conversion.
Related Tools
For material weight, Material Weight Calculator. For hardness conversion, Hardness Conversion. For thread specs in metric/imperial, Thread Pitch.