Emission Rate Calculator
Burning fuel releases carbon dioxide at a rate fixed by chemistry, not by the vehicle or boiler doing the burning: about 8.78 kg of CO2 per gallon of gasoline, 10.21 kg per gallon of diesel, and 5.30 kg per therm of natural gas. Pick a fuel, enter how much you used, and this calculator returns your total CO2 in kilograms and metric tons, the emission rate per unit for that fuel, and your fuel efficiency if you add the distance traveled. An optional electricity field adds grid emissions at the US average rate, so a tank of fuel and a month of power can be totaled in one place. Every factor is published in the table further down, with its source, so you can check the numbers instead of trusting them.
Combustion CO2 only (Scope 1 style); excludes fuel production and transport. Electricity uses the US average grid mix: adjust if your region differs.
Quick Answer
The worked example in the calculator, 10 gallons of gasoline plus 100 kWh of electricity over 250 miles, totals 124.80 kg of CO2 (0.1248 metric tons): 87.80 kg from the fuel at a rate of 8.78 kg per gallon, plus 37.00 kg from the electricity, at 25.0 mpg.
Key takeaways
- An emission rate is a per-unit figure: total CO2 is always quantity multiplied by the rate for that fuel and unit. Change the unit and the rate changes with it.
- Diesel emits about 16% more CO2 per gallon than gasoline. Diesel vehicles often still win per mile because they burn fewer gallons, which is why the tool reports efficiency alongside the total.
- Electricity is not zero-emission in this accounting: at the US average grid rate, 100 kWh adds 37.00 kg, roughly the same as burning 4.2 gallons of gasoline.
- These are combustion figures only. Fuel production, refining, delivery, and non-CO2 gases sit outside the total, so a full lifecycle number would run higher.
- Quick Answer
- How to use the emission rate calculator
- The formula: quantity times a published emission factor
- Every emission factor this tool uses, with its units checked
- Worked examples: four runs through the tool
- What emission rate means here, and what stays outside it
- What competing emission calculators miss
- Frequently asked questions
- Add This Calculator to Your Website
- References
How to use the emission rate calculator
Start with the fuel and work left to right. Results stay hidden until you press Calculate, and Reset returns the calculator to the worked example below so you can start again from known numbers.
- Fuel type: gasoline, diesel, natural gas, coal, propane, or heating oil. The Unit list rebuilds itself for the fuel, because quoting natural gas in gallons or coal in therms would be nonsense.
- Unit and quantity: enter how much you burned in the unit shown, such as gallons from a fuel receipt, therms from a gas bill, or kilograms of coal.
- Electricity (optional): add kWh from a power bill if you want fuel and electricity in one total. If you track what that electricity costs as closely as what it emits, the cost per kWh calculator covers the money side of the same bill.
- Distance (optional): add miles or kilometers traveled on that fuel to get an efficiency figure, mpg or L/100km, beside the emissions total.
The output gives you three things in order: the combined total in kg and metric tons, a line-by-line breakdown showing each multiplication, and the emission rate itself. Keep the rate line if you are filling in a report or spreadsheet: it is the figure an auditor can trace back to the published EPA and EIA factors in the table below.
The formula: quantity times a published emission factor
There is no hidden model here. For each fuel, total emissions are the quantity burned multiplied by that fuel’s emission factor, exactly as set out in the EPA Emission Factors for Greenhouse Gas Inventories, and electricity follows the same pattern with a grid factor.
Emission rate = the factor itself, in kg CO2 per gallon, liter, therm, cubic foot, kilogram, pound, or kWh
Fuel efficiency = Distance ÷ Quantity (mpg), or Quantity ÷ Distance × 100 (L/100km)
Why the factors differ comes down to carbon content and energy density. A gallon of diesel packs more carbon than a gallon of gasoline, so it releases more CO2 when burned, a point the EPA’s own vehicle guidance makes when it notes that diesel’s higher per-gallon figure is partly offset by better fuel economy. Coal is measured by weight rather than volume, and its factor here is an all-types average: specific coals run higher or lower, which is one reason a coal cost calculator and this tool answer different halves of a coal question, price versus emissions. Natural gas burns cleaner per unit of energy than either liquid fuel, which the per-therm figure reflects.
Every emission factor this tool uses, with its units checked
All factors are kilograms of CO2 per unit, from the EPA Emission Factors Hub and the EIA’s carbon dioxide emissions coefficients by fuel. The pairs were cross-checked for unit consistency: a per-liter factor multiplied by 3.78541 liters per gallon should land on the per-gallon factor, and it does within rounding (gasoline: 2.32 × 3.78541 = 8.78; diesel: 2.70 × 3.78541 = 10.22 against a published 10.21).
| Fuel | Rate, first unit | Rate, second unit | Note |
|---|---|---|---|
| Gasoline | 8.78 kg / gallon | 2.32 kg / liter | Standard motor gasoline |
| Diesel | 10.21 kg / gallon | 2.70 kg / liter | Highest per gallon of the road fuels |
| Natural gas | 5.30 kg / therm | 0.0529 kg / cubic foot | Therms are how US gas bills are written |
| Coal | 1.94 kg / kilogram | 0.88 kg / pound | All-types average; bituminous runs higher |
| Propane | 5.75 kg / gallon | 1.52 kg / liter | LPG burned as fuel |
| Heating oil | 10.19 kg / gallon | 2.69 kg / liter | Distillate fuel oil, close to diesel |
Per gallon, the liquid fuels rank like this:
One display detail worth knowing: the Unit dropdown rounds the natural gas cubic-foot rate to 0.05 kg in its label, because the label shows two decimals. The calculation itself uses the full 0.0529 kg factor, so totals are not affected by the rounded label. If a figure ever looks off by a few percent on cubic feet, that label is the first place to look, and the breakdown line under your result always prints the true rate used, to four decimals.
Worked examples: four runs through the tool
Each row below is an actual calculator output, produced by running the tool code on these inputs.
| Run | Total CO2 | Rate and efficiency shown |
|---|---|---|
| 10 gal gasoline + 100 kWh + 250 miles | 124.80 kg (0.1248 t) | 8.78 kg per gallon; 25.0 mpg |
| 20 liters diesel + 500 km | 54.00 kg (0.0540 t) | 2.70 kg per liter; 4.0 L/100km |
| 100 therms natural gas, no extras | 530.00 kg (0.5300 t) | 5.30 kg per therm |
| 500 lb coal, no extras | 440.00 kg (0.4400 t) | 0.8800 kg per pound |
The first run is the page’s worked example and the calculator’s pre-filled state. Notice how the total is built: the fuel line and the electricity line are computed separately and then added, so you can defend either half on its own. A household working through a full energy picture, fuel plus power plus heating, can run each source once and add the totals, or use the combined field for the two biggest ones. For the spending side of the same exercise, the cost of energy calculator prices the consumption this tool weighs.
What emission rate means here, and what stays outside it
Emission rate on this page means the CO2 released per unit of fuel burned, the factor in the table. It is a property of the fuel, not of your engine: a gallon of gasoline holds the same carbon whether a compact car or a truck burns it, and the engine only decides how many gallons a mile takes. That is why the tool can honestly report an efficiency figure next to the rate without the two contradicting each other.
The boundary matters for reporting. The total here is direct combustion CO2, the Scope 1 style figure in greenhouse gas accounting, plus a Scope 2 style electricity line at a national average grid rate. It excludes the emissions from producing, refining, and delivering the fuel, which a full lifecycle or well-to-wheel figure would add, and it excludes non-CO2 gases such as methane leakage from gas systems. The EIA environment data pages are a good next read if you need sector-level totals to set your own figure against. If your utility publishes its own grid intensity, compute the electricity portion separately with that rate rather than the 0.37 average: a coal-heavy grid runs well above it and a hydro-heavy grid well below.
What competing emission calculators miss
- Hidden or stale factors. Many tools never show the factor behind the total, and several still use 8.89 kg per gallon for gasoline, an older EPA equivalencies figure. This page uses the current EPA Hub factor of 8.78 and prints every factor with its source before you calculate.
- One fuel, one unit. Vehicle-only tools cannot take a gas bill in therms or a coal delivery in pounds. Here each of the six fuels carries its own honest units, and the unit list changes with the fuel.
- No electricity in the same total. Fuel and power usually live in separate calculators, which forces hand-addition and invites double counting. The optional kWh field folds grid emissions into the same run, itemized on its own line.
- Efficiency treated as an afterthought. A per-gallon ranking makes diesel look simply worse. Pairing the total with mpg or L/100km shows the per-mile picture, where burning fewer gallons can outweigh a higher rate.
Frequently asked questions
8.78 kg of CO2 per US gallon, from the EPA Emission Factors Hub. In liters that is 2.32 kg per liter. Some older pages still quote 8.89 kg, an earlier EPA equivalencies figure; this tool uses the current Hub factor and shows it in the Unit dropdown before you calculate.
10.21 kg per gallon, or 2.70 kg per liter, about 16% more than gasoline per gallon because diesel carries more carbon per unit of volume. Diesel vehicles often emit less per mile anyway, since they typically travel further on each gallon, which is why the calculator reports fuel efficiency next to the total.
5.30 kg of CO2 per therm, or 0.0529 kg per cubic foot. A home that burns 100 therms in a cold month therefore produces 530.00 kg of CO2 from gas alone, the third worked example on this page. The dropdown label rounds the cubic-foot rate to 0.05 kg, but the calculation uses the full 0.0529 factor.
0.37 kg of CO2 per kWh, the US average grid mix. It is an average, not a measurement of your supply: a coal-heavy grid runs higher and a hydro or nuclear heavy grid runs lower. If your utility publishes its own intensity figure, calculate the electricity share separately with that rate for a more accurate total.
No. It counts combustion CO2 only. Methane leaked during gas production and delivery, nitrous oxide, and the emissions from refining and transporting fuel all sit outside the total. A full lifecycle or CO2-equivalent figure for the same activity would be higher than the number shown here.
This tool uses 1.94 kg of CO2 per kilogram of coal, an all-types average. Coal grades differ a lot in carbon content: bituminous coal sits above the average and lignite below it, so a source quoting a single grade will show a different number. If you know your grade, treat this result as a central estimate rather than an exact value.
From the distance and quantity you enter. Miles with gallons gives miles per gallon, so 250 miles on 10 gallons is 25.0 mpg. Kilometers with liters gives liters per 100 km, so 20 liters over 500 km is 4.0 L/100km. Mixed combinations, such as miles with liters, are converted and marked as estimated, and efficiency is only computed for liquid fuels.
Only partly. It covers direct fuel combustion across six fuels plus grid electricity, which is the energy core of most footprints. It does not cover food, flights bought as tickets rather than fuel, purchased goods, or waste. Use it for the fuel and energy slice of a footprint, and expect a complete footprint to be larger.
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References
- U.S. Environmental Protection Agency. Emission Factors for Greenhouse Gas Inventories. Accessed October 21, 2026.
- U.S. Energy Information Administration. Carbon Dioxide Emissions Coefficients by Fuel. Accessed October 21, 2026.
- U.S. Energy Information Administration. Environment data and carbon dioxide emissions by fuel. Accessed October 21, 2026.
- U.S. Environmental Protection Agency. Greenhouse Gas Emissions from a Typical Passenger Vehicle. Accessed October 21, 2026.
- U.S. Environmental Protection Agency. Emission Facts: Average Carbon Dioxide Emissions Resulting from Gasoline and Diesel Fuel (EPA 420-F-05-001). Accessed October 21, 2026.