Structural Engineering Unit Converter
Convert between SI and US customary units — force, stress, moment, load, length, area, volume, unit weight, and temperature. Type in any field to instantly convert all others.
Force
About This Unit Converter
This free online unit converter is built for structural and civil engineers who work across multiple design codes and unit systems. Whether you need to convert kN to kip, MPa to ksi, kN/m to kip/ft, or kN·m to kip·ft, the tool handles the most frequently needed SI and US customary conversions in one place — no formula lookup required.
Force conversions include N, kN, MN, kgf, metric ton-force (tf), lbf, and kip. Stress and pressure conversions span Pa, kPa, MPa, GPa, kgf/cm², psi, and ksi — essential when comparing concrete compressive strength, steel yield strength (Fy), or soil bearing capacity between ACI 318, Eurocode 2, IS 456, AISC, and TS 500 standards. Bending moment covers kN·m, kip·ft, and kip·in for beam and column design. Linear load (kN/m ↔ kip/ft) and area load (kN/m² ↔ psf ↔ ksf) are included for slab and frame analysis. Unit weight conversions between kN/m³ and pcf support material density inputs. Length, area, and volume conversions cover mm, cm, m, in, ft, and related derived units. Finally, temperature conversion between °C, °F, and Kelvin supports material specification and thermal load calculations.
SI and US Customary Units in Structural Engineering
Structural engineering uses two primary unit systems: SI (Système International) and US Customary (imperial). SI is based on the metre, kilogram, and second, with derived units including the newton (N = kg·m/s²) and pascal (Pa = N/m²). US Customary uses the foot, pound-force (lbf), and kilopound (kip = 1,000 lbf), with stress expressed in psi or ksi.
Key conversion factors for structural design: Force — 1 kip = 4.44822 kN. Stress — 1 ksi = 6.89476 MPa. Bending moment — 1 kip·ft = 1.35582 kN·m. Distributed load — 1 kip/ft = 14.5939 kN/m. Area load — 1 psf = 0.04788 kPa. Unit weight — 1 pcf = 0.15709 kN/m³. Length — 1 ft = 304.8 mm.
Design codes such as ACI 318, AISC 360, and ASCE 7 use US Customary units in their primary editions. Eurocode 2/3, IS 456, and TSC 2018 (TS 500) use SI exclusively. When applying code equations directly — such as the √f′c shear coefficients in ACI 318 or the γc partial factor in EC2 — values embedded in empirical formulas change numerically between unit systems, so consistent unit conversion at input stage is essential for correct results.