Gas Rate Calculator
Calculate gas rate (m³/hr) and heat input (kW) from your meter readings. Supports metric (m³) and imperial (ft³) meters, natural gas and LPG, optional pressure/temperature correction, and appliance nameplate comparison.
Enter meter start, meter end and test duration to calculate.
How it works
m³/hr = (end − start) ÷ (time ÷ 3600); kW = m³/hr × CV (kWh/m³). The standard UK natural gas calorific value used is 10.94 kWh/m³ (typical billing CV published by National Grid / Cadent — actual regional CV varies 10.5 to 11.5 kWh/m³). LPG (propane) is taken as 26.9 kWh/m³. Use the CV override if you have a more accurate figure for the meter being tested.
Pressure and temperature correction
Gas meters read the volume at meter conditions. For a more accurate heat input, the volume can be corrected back to standard conditions (1013.25 mbar absolute, 15 °C / 288.15 K) using the ideal gas law: Vcorrected = Vmeasured × (P / 1013.25) × (288.15 / T). For most domestic checks the uncorrected value is sufficient.
Imperial meters
Older imperial meters read in ft³. The calculator converts using 1 ft³ = 0.0283168 m³. Useful for older domestic and commercial installations that haven't been swapped to metric.
Used by gas engineers in
- CP12 landlord gas safety record — gas rate is recorded on every appliance check.
- Browse other gas certificate types — commissioning, non-domestic, leisure accommodation, and more.