Fleet Carbon Emissions
Calculate total fleet CO2 emissions across all fuel types.
About this calculator
Every vehicle type in a mixed fleet produces carbon dioxide through a different pathway, so this calculator computes each one separately before combining them into a single total. Gasoline and diesel vehicles burn fuel directly, so their emissions come from dividing annual miles by fuel economy to get gallons consumed, then multiplying by a fixed emission factor per gallon — diesel's factor (22.44 lbs CO2/gallon) is higher than gasoline's (19.6 lbs/gallon) because diesel is a denser fuel that releases more carbon per gallon burned, even though diesel engines are often more fuel-efficient overall. Electric vehicles produce no tailpipe emissions at all, but they're not emissions-free once you account for how the electricity powering them was generated — the calculator converts EV miles into kilowatt-hours consumed, then multiplies by your local grid's carbon intensity, since a kWh generated from a coal-heavy grid carries far more embedded CO2 than the same kWh from a hydro- or nuclear-heavy grid.
That's why the grid carbon intensity input matters so much: an EV fleet in a clean-grid region can show dramatically lower emissions than the identical fleet in a coal-heavy region, even with identical vehicles and mileage. The potential EV reduction figure estimates what your total emissions would look like if every vehicle in the fleet, including the current gasoline and diesel ones, ran on the same grid electricity instead — a useful benchmark for evaluating electrification, though it doesn't account for the embedded manufacturing emissions of building new EVs to replace vehicles you already own.
Inputs
Results
Total CO2 (US Tons)
346.8 tons
≈ 58 elephants
Total CO2 (Metric Tons)
314.6 t
How to Use This Calculator
- Enter the number of Gasoline Vehicles, Diesel Vehicles, and Electric Vehicles in the fleet.
- Set Annual Miles per Vehicle for each fuel type.
- Enter the fleet's average Gasoline MPG, Diesel MPG, and EV Efficiency (mi/kWh).
- Set your local Grid Carbon Intensity (lbs CO2/kWh) — the US average is 0.92.
- Review Total CO2 Tons per year and the per-vehicle breakdown to track emissions reduction progress.
How the result changes with Diesel Fleet MPG
| Diesel Fleet MPG | Total CO2 (US Tons) | Total CO2 (Metric Tons) |
|---|---|---|
| 9 | 521.4 tons | 473 t |
| 14 | 396.7 tons | 359.9 t |
| 27 | 288.7 tons | 261.9 t |
| 30 | 277 tons | 251.3 t |
What each input means
- Gasoline Vehicles
- Number of gasoline-powered vehicles in the fleet.
- Diesel Vehicles
- Number of diesel-powered vehicles in the fleet.
- Electric Vehicles
- Number of battery electric vehicles in the fleet.
- Gas Vehicle Annual Miles
- Annual miles per gasoline vehicle.
- Diesel Vehicle Annual Miles
- Annual miles per diesel vehicle.
- EV Annual Miles
- Annual miles per electric vehicle.
- Gasoline Fleet MPG
- Average fuel economy of gasoline vehicles.
- Diesel Fleet MPG
- Average fuel economy of diesel vehicles.
- EV Efficiency
- Average EV efficiency in miles per kWh.
- Grid Carbon Intensity
- CO2 per kWh from your electric grid (US avg: 0.92).
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersGasoline Vehicles = 15, Diesel Vehicles = 8, Electric Vehicles = 2, Gas Vehicle Annual Miles = 25000 = 10 input(s) provided
- Calculate Total CO2Total CO2346.8 = 346.8
- Calculate Total CO2Total CO2314.6 = 314.6
- Calculate CO2 per MileCO2 per Mile1 = 1
- Calculate CO2 per VehicleCO2 per Vehicle27747 = 27747
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does diesel have a higher CO2-per-gallon factor than gasoline despite often getting better MPG?
Diesel fuel is denser than gasoline and contains more carbon atoms per gallon, so burning one gallon of diesel releases more CO2 than burning one gallon of gasoline, independent of how efficiently the engine uses that fuel. A diesel vehicle's typically better fuel economy can still leave it emitting less total CO2 per mile than a gasoline vehicle, but the per-gallon emission factor itself is higher for diesel.
Why would an EV fleet's emissions change if I don't change anything about the vehicles?
EV emissions in this calculator are entirely a function of the grid carbon intensity you enter, since the vehicles themselves produce no tailpipe emissions — all of their footprint comes from generating the electricity they consume. If your local utility shifts toward more renewable generation and grid carbon intensity drops, the identical EVs driving the identical miles will show lower calculated emissions without anything about the fleet itself changing.
Does the potential EV reduction figure account for the emissions from manufacturing new EVs?
No — it only compares the operational emissions of running the current fleet mix against running the same total mileage entirely on grid electricity, without accounting for the manufacturing footprint of producing replacement vehicles. Manufacturing emissions for a new EV can be meaningfully higher than for a comparable gas vehicle, which the full lifecycle picture would need to offset against operational savings over time.
Why is the CO2-per-mile figure useful alongside the total tons figure?
Total CO2 tons scales with your fleet size and mileage, making it hard to compare fleets of different sizes on equal footing, while CO2 per mile normalizes for that and reflects the underlying efficiency and fuel mix of the fleet itself. A smaller fleet with a worse fuel mix can show a lower total but a worse per-mile figure than a larger, cleaner fleet.
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