How is this calculated?
Gallons needed = distance / MPG Total cost = gallons needed * price per gallon Cost per mile = price per gallon / MPG Metric liters = (distance km * L/100 km) / 100 CO2 gasoline estimate = gallons * 8.89 kg
Example: a 300-mile trip at 28 MPG uses 10.71 gallons. At $3.50 per gallon, the one-way fuel cost is $37.50 and gasoline CO2 is about 95.3 kg.
How do I use this calculator?
- Choose the unit or currency setting that matches your vehicle data.
- Enter the required vehicle, route, fuel, weight or loan values in the calculator form.
- Review inline warnings and correct any missing or negative inputs.
- Read the live result card for the primary answer and supporting totals.
- Use the worked example if you want to check the formula with sample values.
- Copy, share or print the results for comparison or record keeping.
What do the terms mean?
- MPG
- Miles per gallon, used for US trip estimates.
- L/100 km
- Liters per 100 kilometers, common outside the US.
- Round trip
- The outbound distance doubled for a return journey.
- CO2 estimate
- Approximate tailpipe carbon dioxide from fuel burned.
- Cost per mile
- Trip fuel cost divided by trip distance.
What are real-world examples?
| Scenario | Inputs | Result | Notes |
|---|---|---|---|
| Daily commute | 32 mi, 30 MPG | $3.73 | One-way at $3.50/gal |
| Weekend road trip | 300 mi, 28 MPG | $37.50 | Gasoline |
| Diesel pickup | 180 mi, 17 MPG | $42.35 | $4.00/gal diesel |
| Metric van route | 420 km, 9.5 L/100 km | 39.9 L | Multiply by price/L |
What tips improve accuracy?
- Use real observed MPG rather than window-sticker ratings for trip budgets.
- Add 5% to 15% for mountains, winter fuel, headwinds or stop-and-go traffic.
- Diesel emits about 10.18 kg CO2 per gallon; gasoline about 8.89 kg.
- Tolls, parking and hotel charging are separate from fuel cost.
- For towing, use your towing MPG rather than unloaded MPG.
- Check tire pressure before long trips to reduce waste.
Did you know? EPA estimates commonly use 8.89 kg CO2 per gallon of gasoline and 10.18 kg CO2 per gallon of diesel for tailpipe carbon dioxide calculations.
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Frequently asked questions
Is this calculator free to use?
Yes. The calculator runs in your browser, does not require an account and can be printed or copied for your records.
Can I use this for official tax, loan or compliance filing?
Use it as an estimate. For official filing, financing or enforcement decisions, verify the final numbers with your lender, tax authority, manufacturer rating label or compliance professional.
Why are my real-world results different?
Real vehicles vary with load, speed, terrain, temperature, tire condition, maintenance, driver behavior and measurement quality.
Does the calculator save my units?
Yes. Unit and currency selections that are marked as preferences are stored in localStorage on your device so the next visit starts with your preferred setting.
Can I share the result?
Yes. Use the Share button if your browser supports native sharing, or copy the permalink and result summary.
Does it work on mobile?
Yes. The layout stacks on small screens, keeps labels visible and recalculates as you type.
How accurate are the formulas?
The formulas are standard industry math for estimates. Accuracy depends on the input values and whether the assumptions match your vehicle and jurisdiction.
When was this page updated?
This page was last updated on 2026-05-01 for 2026 planning assumptions and source links.