Natural Gas Therms to CO₂ Calculator
Convert natural gas use (in therms) into estimated carbon emissions (kg CO₂). Enter your usage to see the result and how it is worked out.
therms
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How it's calculated
The calculation is a single multiplication:
kg CO₂ = natural gas used (therms) × 5.3 (kg CO₂ per therm)
Emission factor: 5.3 kg CO₂ per therm. Source: US EPA, pipeline natural-gas combustion. Boundary: Combustion only; excludes upstream methane leakage. Factor vintage: 2024.
Accuracy and limitations
- The factor covers carbon dioxide from burning pipeline natural gas, not unburned methane leakage upstream or at the property.
- A therm is 100,000 British thermal units. Bills based on volume use a heat-content factor that can vary by supplier and billing period.
- Use the therm total printed by the supplier instead of converting cubic feet with a generic factor when possible.
Frequently asked questions
How do you convert therms to CO₂?
Multiply therms used by an emission factor in kg CO₂ per therm. A therm is a fixed unit of heat energy, so the factor is stable for natural gas combustion.
Where do I find my therms used?
Your gas bill usually lists usage in therms or in CCF/cubic feet. If it shows CCF, your supplier also prints a therm factor to convert it — use the therm value here.
Does this include upstream methane leakage?
No. This EPA equivalency covers CO₂ released when natural gas is burned. A full lifecycle estimate would also include production, processing, transmission and leakage.