13. Conversion factors

Metric and British units

 To obtain From Multiply by the following 3.281 metres (m) feet (ft) 0.3048 10.76 square metres (m2 ) square feet (ft 2 ) 0.0929 35.32 cubic metres (m³) cubic feet (ft 3 ) 0.0283 0.22 litres (l) UK gallons (UK gal) 4.546 0.264 litres (l) US gallons (US gal) 3.785 0.0353 litres (1) cubic (ft3) 28.3168 2.205 kilogrammes (kg) pounds (lb) 0.454 0.00142 kilogrammes per square metre (kg/m²) pounds per square inch (lb/in2) 703 0.0624 kilogrammes per cubic metre (kg/m³) pounds per cubic foot (lb/ft3) 16.0185 3.97 kilocalories (kcal) British thermal units (Btu) 0.252 1.341 kilowatts (kW) horsepower (hp) (UK or US) 0.746 0.00156 kcal per hour (kcal/h) hp 642 1.163 kcal/h x 1000 kilowatts (kW) 0.860 0.3307 kcal/h x 1000 ton of refrigeration (US) 3.024 0.2048 keal/m²h°C Btu/ft 2 h°F 4.882 8.064 kcal/m h°C Btu in/ft 2 h°F 0.1240 1 kcal/kg °C Btu/lb °F 1 1.8 kcal/kg Btu/lb 0.5556 Multiply by the above To convert To

Metric, Imperial and SI units

The International System of Units (SI units) is now widely used and some conversions relating to the above units are given below:

 To obtain From Multiply by the following 9.807 kg/m² Newtons per square metre, Pascals (N/m²) (Pa) 0.1020 0.9807 kg/m² milk bar (mbar) 1.020 6895 lb/in2 (psi) Pascals (N/m²) (Pa) 0.000145 0.01450 mbar lb/in 2 ( psi ) 68.95 4.187 kcal kilojoules (kJ) 0.2388 0.9479 kJ Btu 1.055 1.163 kcal x 1000 kWh 0.8598 0.2778 MJ kWh 3.6 3.413 W Btu/h 0.293 1.341 kW hp (UK & US) 0.746 1.359 kW hp (metric) 0.736 12 ton refrigeration (US) Btu/h x 1000 0.08333 3.517 ton refrigeration kW 0.284 1.163 kcal/h W 0.8598 1.163 kcal/m²h0C W/m² °C 1 0.8598 0.317 W/m² Btu/ft 2 h 3.155 0.1761 W/m² °C Btu/ft 2 h°F 5.678 1.163 kcal/m h°C W/m °C 0.8598 6.935 W/m °C Btu/in/ft 2 h°F 0.1442 0.2388 kcal/kg °C kJ/kg°C 4.187 0.2388 kJ/kg °C Btu/lb °F 4.187 Multiply by the above To convert To