Unit Converter

Engineering Unit Converter

Type in any field — all related units update instantly. Covers length, area, volume, mass, force, stress, moment and temperature.

📏 Length
⬜ Area
📦 Volume
⚖ Mass / Weight
➗ Linear Mass (kg/m → lb/ft)
⚙ Force
🔩 Pressure / Stress
🔖 Common Steel Grades
S235 fy
235 MPa = 34.1 ksi
S275 fy
275 MPa = 39.9 ksi
S355 fy
355 MPa = 51.5 ksi
S420 fy
420 MPa = 60.9 ksi
A36 Fy
250 MPa = 36.3 ksi
A572 Gr50 Fy
345 MPa = 50.0 ksi
📐 Bending Moment / Torque
🌡 Temperature
🔖 Engineering References
Steel ambient (design)
20 °C = 68 °F
Steel melting point (approx)
1370–1510 °C
Charpy test — J0 sub-grade
0 °C = 32 °F
Charpy test — J2 sub-grade
−20 °C = −4 °F
Fire design ref. temperature
500–700 °C typical
Thermal expansion steel
12 × 10−6 /°C

Unit Systems Used in Structural Engineering

Structural engineering practice spans two primary unit systems: the International System of Units (SI), used throughout Europe, India, and most of the GCC, and the US Customary (Imperial) system, used in American practice under AISC, ASTM, and ASME standards. Converting accurately between these systems is critical on projects where both sets of standards are referenced — particularly common in GCC EPC projects where API, ASME, and AISC codes (Imperial) coexist with Eurocode and IS standards (SI).

Length and Dimension Conversions

The fundamental length conversion is: 1 inch = 25.4 mm (exact). From this, all other length conversions follow. Key values used in structural engineering:

  • 1 foot (ft) = 304.8 mm = 0.3048 m
  • 1 inch (in) = 25.4 mm
  • 1 metre (m) = 3.2808 ft = 39.3701 in
  • 1 millimetre (mm) = 0.03937 in

Section dimensions in EN tables are in millimetres; AISC tables use inches. When checking section compatibility or comparing profiles across standards, always convert before comparing flange width, depth, and wall thickness.

Force and Stress Conversions

Structural loads and material strengths are expressed differently across standards. The key conversions are:

  • 1 kN = 0.2248 kips (1 kip = 4.4482 kN)
  • 1 kN/m² (kPa) = 0.02089 ksf = 0.1450 psi
  • 1 MPa (N/mm²) = 0.1450 ksi (1 ksi = 6.8948 MPa)
  • 1 kN·m = 0.7376 kip·ft = 8.8507 kip·in

Steel yield strength is commonly expressed as MPa in Eurocode and IS practice (e.g. S355 = 355 MPa) and ksi in AISC (e.g. A572 Grade 50 = 50 ksi = 344.7 MPa). These are effectively equivalent for most practical purposes.

Mass and Weight Conversions

Steel section linear mass (kg/m) must frequently be converted to lb/ft for AISC sections or for projects using Imperial weight schedules:

  • 1 kg/m = 0.6720 lb/ft
  • 1 lb/ft = 1.4882 kg/m
  • 1 tonne (metric ton) = 1000 kg = 2204.6 lb = 1.1023 short tons
  • 1 kN = 101.97 kgf ≈ 0.102 tonnes-force

On GCC projects, material take-off (MTO) quantities are typically reported in metric tonnes. API pipe specifications list nominal wall thickness and weight in both metric and Imperial units — always verify the system before entering values into calculations.

Section Modulus and Moment of Inertia Conversions

Section properties appear in cm³ and cm⁴ (EN tables), in³ and in⁴ (AISC tables), and occasionally mm³ and mm⁴ in calculation outputs. The conversions are:

  • 1 cm⁴ = 10−8 m⁴ = 10⁴ mm⁴ = 0.02403 in⁴
  • 1 in⁴ = 41.623 cm⁴
  • 1 cm³ = 10³ mm³ = 0.06102 in³
  • 1 in³ = 16.387 cm³

These conversions are especially important when inputting section modulus values from EN tables into AISC-based spreadsheets, or when checking LTB capacity using mixed-standard inputs.

Temperature and Thermal Properties

GCC projects often require thermal expansion calculations for steel structures exposed to extreme ambient temperatures (up to 51°C in Riyadh and 45°C in Doha). The coefficient of thermal expansion for structural carbon steel is α = 12×10−6 /°C (EN 1991-1-5). Temperature conversion: °C = (°F − 32) × 5/9.