This CO2 emissions calculator estimates carbon dioxide from fuel burned — driving by distance and economy, fuel by the gallon/litre, or flights by distance — using standard emission factors.
Fuel Burned × Emission Factor — Carbon Is Bookkeeping on Combustion
Every litre of gasoline contains a fixed carbon endowment that exits as ~2.31 kg of CO₂; the chemistry permits no negotiation, only arithmetic. The whole-household ledger is our Carbon Footprint Calculator. Part of our Ecology Calculators collection.
Worked Examples (Verified)
- 12,000 miles/yr at 28 MPG (defaults): 428.6 gal × 8.887 = 3,809 kg ≈ 3.8 tonnes CO₂/yr — the average US driver's personal exhaust pipe
- Fuel anchor: 10 gallons of gasoline = 88.9 kg CO₂; the same volume of diesel = 101.8 kg (denser carbon per litre, partially offset by diesel efficiency in practice)
- Flight comparison: NYC–LA round trip ≈ 4,900 passenger-miles × 0.20 ≈ 980 kg — one trip ≈ a quarter of the driving year above
- The EV contrast: the same 12,000 miles on a US-average grid lands near 1.2–1.7 tonnes — our EV Savings Calculator prices the money twin of this calculation
Scope Honesty
- Tailpipe vs lifecycle: fuel production adds ~20–25% (well-to-tank); aircraft non-CO₂ effects may multiply climate impact — conventions are stated so your totals can be compared like-for-like.
- Occupancy divides: a car's per-passenger figure halves with two occupants; flights are already per-passenger by construction.
- Offsets are a separate ledger (and quality varies wildly); this page measures the emission, not the absolution.
- Grid electricity varies ~5× by region — driving factors here are fuel-only by design.
Related Tools
- Carbon Footprint Calculator — the full household footprint
- EV Savings Calculator — electric miles, priced
- Ecology Calculators — the full collection
Frequently Asked Questions
How much CO2 does a gallon of gasoline produce?
8.887 kg (EPA factor) when burned — the carbon in the fuel plus the oxygen it grabs, which is why exhaust CO₂ outweighs the fuel itself. Diesel is 10.18 kg/gallon (2.68 kg/L vs gasoline's 2.31 kg/L). This calculator applies the factors to driving, direct fuel use, or flights.
How much CO2 do I emit driving per year?
Miles ÷ MPG × 8.887 kg. The US-typical 12,000 miles at 28 MPG gives ≈ 3.8 tonnes. Halve it by doubling economy or occupancy; the formula has no other levers — which is the entire policy debate in one line of arithmetic.
How much CO2 is a flight?
Roughly 0.15–0.25 kg per passenger-mile depending on haul length and load factor (this tool blends 0.20): a transcontinental US round trip ≈ 1 tonne per passenger. Short hops are worse per mile (takeoff dominates); first-class seats multiply by footprint share of cabin space.
Why do different calculators give different flight numbers?
Two choices: the per-mile factor (aircraft, load factor, routing) and whether to apply a radiative-forcing multiplier (~1.7–1.9×) for high-altitude non-CO₂ effects. This page reports CO₂ only and says so — add the multiplier yourself if your accounting standard requires it; both conventions are defensible, mixing them silently isn't.
How many trees offset a tonne of CO2?
A mature tree sequesters roughly 20–25 kg CO₂/year, so a tonne ≈ 40–50 tree-years of growth — the scale intuition behind our Tree Carbon Calculator's per-tree storage figures. Offsets via planting are slow, reversible storage; emission cuts are immediate. The calculator measures; priorities are yours.
Is this CO2 emissions calculator free?
Yes — free, instant, no sign-up.