Structural Unit Converter

Convert between metric and imperial units used in structural engineering. Select a category, enter a value, and see all conversions instantly.

Why Unit Conversion Matters in Structural Engineering

Mixing up units is one of the most common and dangerous sources of error in structural engineering. International projects routinely require switching between SI (metric) and US customary (imperial) systems. A misplaced factor of 25.4 between millimetres and inches, or confusing kN with kip, can lead to members sized incorrectly by an order of magnitude. Reliable, instant unit conversion removes this risk from everyday calculations.

Common Structural Engineering Units

Length — Dimensions and spans are specified in mm or m (metric) and inches or feet (imperial). Most design codes and section catalogues use mm for cross-section dimensions and m for member lengths.

Force — Loads and reactions are expressed in kN (metric) or kip (imperial, equal to 1000 lbf). Self-weight calculations often start in kgf or lbf.

Stress & Pressure — Material strengths and calculated stresses use MPa (N/mm²) in metric codes and ksi (kip/in²) in US codes. 1 ksi ≈ 6.895 MPa.

Moment — Bending moments appear as kN·m in metric design and kip·ft in US practice. Getting the conversion right is critical for beam and column checks.

Area, Moment of Inertia & Section Modulus — Section properties come in mm²/mm³/mm⁴ or in²/in³/in⁴. These higher-order units amplify small length errors, making accurate conversion essential.

Distributed Load — Line loads on beams are given in kN/m (metric) or kip/ft (imperial). Consistent units here feed directly into shear and moment diagrams.

Quick Reference: Key Conversions

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