Quick answer
Annual emissions ≈ miles × 3.93 × 10⁻⁴ + kWh × 3.94 × 10⁻⁴ + therms × 5.3 × 10⁻³ (metric tons CO₂e). Driving 12,000 miles, using 10,500 kWh and 400 therms gives 10.973 t: driving 4.716 t, electricity 4.137 t and gas 2.12 t.
Enter yearly miles driven, electricity and natural gas use. The calculator returns total and per-source emissions. Use this carbon footprint estimate calculator to check your own figures.
Related tools: Tree Carbon Uptake Estimate Calculator: Carbon dioxide removed by planted tree seedlings and by forest land, using US EPA factors. Recycling Rate Calculator: Share of waste that is recycled or diverted. Wind Power Estimate Calculator: Power from a wind turbine rotor at a wind speed.
How to use the Carbon Footprint Estimate Calculator
- Enter miles driven per year (average passenger car) (0 or more). It starts at 0.
- Enter electricity used per year (kWh) (0 or more). It starts at 0.
- Enter natural gas used per year (therms) (0 or more). It starts at 0.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Miles driven per year (average passenger car) | A number | ≥ 0, starts at 0 |
| Electricity used per year (kWh) | A number | ≥ 0, starts at 0 |
| Natural gas used per year (therms) | A number | ≥ 0, starts at 0 |
Formula and method
Formula
tons CO₂e = miles × 3.93×10⁻⁴ + kWh × 3.94×10⁻⁴ + therms × 5.3×10⁻³ (metric tons)
IEEE-754 double precision; shown to at most 6 decimal places.
Multiplies each activity by the US EPA Greenhouse Gas Equivalencies factor: 3.93×10⁻⁴ metric tons CO₂e per mile for the average US passenger vehicle (2022 data), 3.94×10⁻⁴ metric tons CO₂ per kWh for the national average electricity mix (eGRID2022) and 5.3×10⁻³ metric tons CO₂ per therm of natural gas. The factors are US averages: your own car, local grid and fuel will differ, and air travel, food and goods are not included.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Miles driven per year (average passenger car) = 12000; Electricity used per year (kWh) = 10500; Natural gas used per year (therms) = 400.
| Result | Value |
|---|---|
| Estimated emissions | 10.973 metric tons CO₂e per year |
| Driving | 4.716 t |
| Electricity | 4.137 t |
| Natural gas | 2.12 t |
| In kilograms | 10,973 kg |
Example 2
Inputs: Miles driven per year (average passenger car) = 0; Electricity used per year (kWh) = 0; Natural gas used per year (therms) = 0.
| Result | Value |
|---|---|
| Estimated emissions | 0 metric tons CO₂e per year |
| Driving | 0 t |
| Electricity | 0 t |
| Natural gas | 0 t |
| In kilograms | 0 kg |
Example 3
Inputs: Miles driven per year (average passenger car) = 5000; Electricity used per year (kWh) = 0; Natural gas used per year (therms) = 0.
| Result | Value |
|---|---|
| Estimated emissions | 1.965 metric tons CO₂e per year |
| Driving | 1.965 t |
| Electricity | 0 t |
| Natural gas | 0 t |
| In kilograms | 1,965 kg |
The first line is the headline result (estimated emissions). Below it the carbon Footprint Estimate Calculator lists driving, electricity, natural gas and in kilograms, which describe the same case from other angles. IEEE-754 double precision; shown to at most 6 decimal places.
US average factors
The factors are US averages: 0.393 kg CO₂e per mile for a typical car, 0.394 kg per kWh for the grid and 5.3 kg per therm of natural gas. Your local grid may be cleaner or dirtier.
What is excluded
Flights, food, waste and purchases are not included, so the total is a partial footprint. The average American's full footprint is often quoted at about 16 t. Use it for relative comparison, not for offsets.
How the result changes with miles driven per year
Holding every other input at the first worked example, this table changes only miles driven per year. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Miles driven per year | Estimated emissions | Driving | Electricity |
|---|---|---|---|
| 6000 | 8.615 metric tons CO₂e per year | 2.358 t | 4.137 t |
| 12000 | 10.973 metric tons CO₂e per year | 4.716 t | 4.137 t |
| 24000 | 15.689 metric tons CO₂e per year | 9.432 t | 4.137 t |
| 48000 | 25.121 metric tons CO₂e per year | 18.864 t | 4.137 t |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Miles driven per year (average passenger car): left empty shows "Enter miles driven per year (average passenger car)." beside that field and no result.
Choosing between the Carbon Footprint Estimate Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Tree Carbon Uptake Estimate Calculator](/science/tree-carbon-uptake-estimate-calculator/) | urban tree seedlings planted and grown for 10 years, acres of US forest and years of forest growth | Carbon dioxide removed |
| [Recycling Rate Calculator](/science/recycling-rate-calculator/) | recycled or diverted and total waste generated | Recycling rate |
| [Wind Power Estimate Calculator](/science/wind-power-estimate-calculator/) | rotor diameter, wind speed and power coefficient | Power |
| [Fuel Emissions Calculator](/science/fuel-emissions-calculator/) | fuel and fuel burned | CO₂ emitted |
| [Travel Emissions Calculator](/science/travel-emissions-calculator/) | distance traveled and emission factor | CO₂ emitted |
Background: environment and acoustics
Decibels are a logarithmic scale, so sound levels cannot be added arithmetically: two equal sources raise the level by about 3 dB, not double it. Environmental and emissions results depend on the factors behind them (for example the US EPA's equivalency factors), which are averages for a country, fuel and year.
Use the result to compare scenarios rather than as a measured value.
Assumptions and limitations
- US average factors only
- Flights, food, waste and purchases are not included
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for miles driven per year (average passenger car) to confirm this.
Frequently asked questions
How can I reduce my footprint?
Drive less, improve insulation and choose clean electricity.
What is CO₂e?
Carbon dioxide equivalent of all greenhouse gases.
Are these factors current?
They are averages and change over time.
What does the Carbon Footprint Estimate Calculator calculate?
Annual greenhouse-gas emissions from driving, home electricity and natural gas using US EPA emission factors. It returns Estimated emissions, Driving, Electricity, Natural gas and In kilograms.
What formula does the Carbon Footprint Estimate Calculator use?
tons CO₂e = miles × 3.93×10⁻⁴ + kWh × 3.94×10⁻⁴ + therms × 5.3×10⁻³ (metric tons). Multiplies each activity by the US EPA Greenhouse Gas Equivalencies factor: 3.93×10⁻⁴ metric tons CO₂e per mile for the average US passenger vehicle (2022 data), 3.94×10⁻⁴ metric tons CO₂ per kWh for the national average electricity mix (eGRID2022) and 5.3×10⁻³ metric tons CO₂ per therm of natural gas.
What do I need to enter in the carbon Footprint Estimate Calculator?
You enter Miles driven per year (average passenger car), Electricity used per year (kWh) and Natural gas used per year (therms).
How is the result rounded or limited?
IEEE-754 double precision; shown to at most 6 decimal places. US average factors only.
What are the limits of this calculator?
US average factors only. Flights, food, waste and purchases are not included.
What is an example of a carbon Footprint Estimate result?
With miles driven per year (average passenger car) 12000, electricity used per year (kWh) 10500 and natural gas used per year (therms) 400, the estimated emissions is 10.973 metric tons CO₂e per year.
Where does the method come from?
The method follows: US EPA, Greenhouse Gases Equivalencies Calculator – Calculations and References (https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references; US government, public domain); EPA Inventory of US Greenhouse Gas Emissions and Sinks 1990–2022; eGRID2022.
Related calculators
- Tree Carbon Uptake Estimate Calculator — Carbon dioxide removed by planted tree seedlings and by forest land, using US EPA factors.
- Recycling Rate Calculator — Share of waste that is recycled or diverted.
- Wind Power Estimate Calculator — Power from a wind turbine rotor at a wind speed.
- Fuel Emissions Calculator — CO₂ from burning gasoline or diesel.
- Travel Emissions Calculator — CO₂ from a trip at an emission factor you enter.
- Point Estimate Calculator — Point estimates of a proportion (MLE, Laplace and Wilson).
Sources
- US EPA, Greenhouse Gases Equivalencies Calculator – Calculations and References (https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references; US government, public domain)
- EPA Inventory of US Greenhouse Gas Emissions and Sinks 1990–2022; eGRID2022
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.