Good to know
- kg is a mass, not a force. 1 kgf (kilogram-force) is the weight of 1 kg in standard gravity, 9.80665 N. When a load is given "in kg", it means kgf – roughly 1 kN ≈ 100 kg.
- N/mm² = MPa. Steel S235 has a yield strength of 235 N/mm², concrete C30/37 a characteristic cylinder strength of 30 N/mm².
- kN/m² = kPa. The imposed load on a residential floor in Eurocode is 1.5–2.0 kN/m² – roughly 150–200 kg per square metre.
- Second moment of area (I) is in cm⁴ in European steel tables and in in⁴ in American ones – 1 in⁴ = 41.62 cm⁴.
The calculator uses the exact definitions: 1 in = 25.4 mm, 1 lb = 0.45359237 kg, g = 9.80665 m/s². The Beam Calculator uses kN, m and cm⁴.