Free Natural Gas Carbon Footprint calculator with clear step-by-step results.
Converts whichever unit your bill uses into kilowatt-hours, applies the combustion factor, then adds an upstream uplift for extraction, processing, transport and methane leakage. That upstream share is commonly 15-25% of the combustion figure and is routinely omitted from household calculations.
Energy content
kWh = amount x conversion factor (1 m3 = 10.55 kWh, 1 therm = 29.31 kWh)
Total emissions
kgCO2e = kWh x combustion factor x (1 + upstream uplift)
Unburned methane has roughly 80 times the warming effect of carbon dioxide over twenty years, so even a leakage rate of 2-3% across the supply chain materially changes the total.
Cubic metres in most of Europe, therms or ccf in the United States, and kWh on many modern smart-meter bills. The conversion above uses standard calorific values.