Gas Safe Engineers Tool
Gas Rate Calculator
Calculate kW heat input from gas flow rate measurements.
Includes temperature and pressure corrections, built-in timer, and appliance identification.
Gas Rate Calculator
Calculate kW heat input from gas flow measurements
Test Parameters
Standard: 15°C
Standard: 1013.25 mbar
00:00
Ready to start
Calculation Method
Heat Input (kW) = Flow Rate (m³/h) × Calorific Value (MJ/m³) ÷ 3.6
Flow rate is corrected to standard conditions (15°C, 1013.25 mbar):
- Temperature correction: (288.15K / Actual Temperature K)
- Pressure correction: (Actual Pressure / 1013.25 mbar)
- Combined correction factor applied to measured flow rate
Standard Calorific Values
Natural Gas (UK):38.5 MJ/m³
LPG Propane:95.8 MJ/m³
LPG Butane:121.8 MJ/m³
Typical Appliance kW Ranges
gas hob:1.5-12 kW
gas oven:2.5-15 kW
combi boiler:24-42 kW
system boiler:15-50 kW
gas fire:2-8 kW
gas heater:3-15 kW
Usage Instructions
- Select gas type (Natural Gas, LPG Propane, or LPG Butane)
- Enter environmental conditions (temperature and atmospheric pressure)
- Use the stopwatch to time your gas flow measurement (recommended: 2+ minutes)
- Enter the measured gas volume and select units (m³/h or l/s)
- Review results including kW heat input, flow rates, and appliance suggestions