UNIT CONVERSION

Bidirectional conversion between SI and US customary units across all engineering domains: length (mm ↔ in), force (N ↔ lbf), pressure (Pa, kPa, bar ↔ psi), energy (J, kJ, kWh ↔ BTU, ft-lbf), power (W, kW ↔ hp), torque (N·m ↔ in-lbf, ft-lbf), viscosity (Pa·s ↔ cP, lb/(ft·s)), thermal conductivity (W/m·K ↔ BTU/(hr·ft·°F)), and temperature (°C, K, °F, °R). Includes density, flow, and concentration conversions.

• 1 lbf = 4.4482 N
• 1 psi = 6894.76 Pa
• 1 BTU = 1055.06 J
• 1 hp = 745.7 W
• T(°F) = T(°C)·1.8 + 32
• 1 cP = 0.001 Pa·s

References & StandardsNIST SP 811, ASTM SI 10, BIPM SI Brochure

Use whenever mixing unit systems: a US specification with European hardware, an ASTM material rating quoted in ksi being matched to an ISO bolt rated in MPa, or converting handbook constants to a consistent system before plugging into a formula. Always verify the conversion by tracking units through the equation rather than trusting a "feel" for the magnitude.