Quick answer
Tailpipe CO₂ = gallons × emission factor. Burning 100 gallons of gasoline at 8.887 kg CO₂ per gallon emits 888.7 kg, or 0.8887 metric tons.
Choose the fuel and enter the amount burned. The calculator returns kg and metric tons of CO₂. Use this fuel emissions calculator to check your own figures.
Related tools: Travel Emissions Calculator: CO₂ from a trip at an emission factor you enter. Electricity Emissions Calculator: CO₂ from electricity use at an emission factor you enter. Greenhouse Gas Conversion Calculator: Convert methane or nitrous oxide to CO₂ equivalent (100-year GWP).
How to use the Fuel Emissions Calculator
- Choose fuel: Gasoline (8.887 kg CO₂ per gallon) and Diesel (10.180 kg CO₂ per gallon).
- Enter fuel burned (US gal) (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Fuel | Choose one: Gasoline (8.887 kg CO₂ per gallon); Diesel (10.180 kg CO₂ per gallon) | Starts at Gasoline (8.887 kg CO₂ per gallon) |
| Fuel burned | A number, in US gal | > 0 |
Formula and method
Formula
CO₂ = gallons × emission factor
IEEE-754 double precision; shown to the decimals indicated.
Tailpipe CO₂ only, using EPA emission factors; upstream emissions are excluded.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Fuel = Gasoline (8.887 kg CO₂ per gallon); Fuel burned = 100.
| Result | Value |
|---|---|
| CO₂ emitted | 888.7 kg CO₂ |
| Metric tons | 0.8887 |
Example 2
Inputs: Fuel = Diesel (10.180 kg CO₂ per gallon); Fuel burned = 55.
| Result | Value |
|---|---|
| CO₂ emitted | 559.9 kg CO₂ |
| Metric tons | 0.5599 |
Example 3
Inputs: Fuel = Gasoline (8.887 kg CO₂ per gallon); Fuel burned = 12.5.
| Result | Value |
|---|---|
| CO₂ emitted | 111.09 kg CO₂ |
| Metric tons | 0.1111 |
The first line is the headline result (cO₂ emitted). Below it the fuel Emissions Calculator lists metric tons, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Factors
The US EPA gives about 8.887 kg CO₂ per gallon of gasoline and 10.18 kg for diesel. A car at 25 mpg driving 12,000 miles burns 480 gallons and emits about 4.3 t.
Tailpipe only
Tailpipe emissions only: the fuel's production, refining and delivery add roughly 20% on top. The Fuel Emissions figure counts CO₂ but not methane or nitrous oxide, which are small.
How the result changes with fuel burned
Holding every other input at the first worked example, this table changes only fuel burned. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Fuel burned | CO₂ emitted | Metric tons |
|---|---|---|
| 50 | 444.35 kg CO₂ | 0.4444 |
| 100 | 888.7 kg CO₂ | 0.8887 |
| 200 | 1,777.4 kg CO₂ | 1.7774 |
| 400 | 3,554.8 kg CO₂ | 3.5548 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Fuel burned: entering "0" shows "Fuel burned must be greater than 0." beside that field and no result.
Choosing between the Fuel Emissions 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 |
|---|---|---|
| [Travel Emissions Calculator](/science/travel-emissions-calculator/) | distance traveled and emission factor | CO₂ emitted |
| [Electricity Emissions Calculator](/science/electricity-emissions-calculator/) | electricity used and emission factor | CO₂ emitted |
| [Greenhouse Gas Conversion Calculator](/science/greenhouse-gas-conversion-calculator/) | gas and mass emitted | CO₂ equivalent |
| [Fuel Cost Calculator](/automotive/fuel-cost-calculator/) | distance, fuel economy and fuel price | Trip cost |
| [Fuel Savings Calculator](/automotive/fuel-savings-calculator/) | miles driven per year, current fuel economy and new fuel economy | Annual savings |
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
- Tailpipe emissions only
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 fuel burned to confirm this.
Frequently asked questions
How much CO₂ per litre of petrol?
Burning a litre of petrol releases about 2.35 kg of CO₂ (8.887 kg per US gallon ÷ 3.785).
Is diesel higher?
Yes, per gallon: about 10.18 kg of CO₂ for diesel against 8.887 kg for gasoline, because diesel is denser.
How do I cut fuel emissions?
Drive less or use a more efficient vehicle.
What does the Fuel Emissions Calculator calculate?
CO₂ from burning gasoline or diesel. It returns CO₂ emitted and Metric tons.
What formula does the Fuel Emissions Calculator use?
CO₂ = gallons × emission factor. Tailpipe CO₂ only, using EPA emission factors; upstream emissions are excluded.
What do I need to enter in the fuel Emissions Calculator?
You enter Fuel and Fuel burned (US gal).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Tailpipe emissions only.
What does the “Fuel” option change?
It sets how the fuel Emissions is worked out. The choices are Gasoline (8.887 kg CO₂ per gallon) and Diesel (10.180 kg CO₂ per gallon).
What is an example of a fuel Emissions result?
With fuel Gasoline (8.887 kg CO₂ per gallon) and fuel burned 100, the cO₂ emitted is 888.7 kg CO₂.
Where does the method come from?
The method follows: US EPA, Greenhouse Gas Equivalencies Calculator – Calculations and References (8,887 g CO₂/gal gasoline; 10,180 g CO₂/gal diesel).
Related calculators
- Travel Emissions Calculator — CO₂ from a trip at an emission factor you enter.
- Electricity Emissions Calculator — CO₂ from electricity use at an emission factor you enter.
- Greenhouse Gas Conversion Calculator — Convert methane or nitrous oxide to CO₂ equivalent (100-year GWP).
- Fuel Cost Calculator — Trip fuel cost from distance, fuel economy and price.
- Fuel Savings Calculator — Yearly fuel savings from a more efficient vehicle.
- Fuel Economy Converter — Convert mpg (US and UK), km/L and L/100 km.
Sources
- US EPA, Greenhouse Gas Equivalencies Calculator – Calculations and References (8,887 g CO₂/gal gasoline; 10,180 g CO₂/gal diesel)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.