A car’s combined fuel economy rating blends city and highway driving. City traffic with stops and starts usually gives 10–20% worse economy, and steady highway driving 10–20% better. Pick a model or enter your own figure.
How to use the Gas Calculator
- Car
- Fuel economy (if Other)
- Trip type
- Distance
- Gas price
- People sharing
Results update as you type, and every field accepts the units shown in its menu.
How it works
Choose a car (or “Other” and enter its mpg), the type of trip, distance, gas price and the number of people sharing.
Tips
- Use your own measured figures – fuel economy, speed and prices vary a lot with driving style, traffic, load and season.
- Pick the unit in each field’s menu (miles or kilometres, mpg or L/100 km); the calculator converts everything for you.
- Fill up to the brim twice and divide the distance by the fuel added to measure real fuel economy.
- For vehicle modifications, treat results as a starting point and confirm with the parts maker or a professional mechanic.
Common mistakes to avoid
- Mixing US and imperial (UK) gallons – a UK gallon is about 20% bigger.
- Using the advertised fuel economy instead of real-world figures.
- Forgetting tolls, parking and wear and tear when comparing driving with public transport.
Inputs explained
| Field | What to enter |
|---|---|
| Car | Choose one: Ford F-150 (≈ 20 mpg), Chevrolet Silverado (≈ 19 mpg), Toyota Camry (≈ 32 mpg), Honda Civic (≈ 35 mpg) … |
| Fuel economy (if Other) | Units: mpg (US), mpg (UK), km/L |
| Trip type | Choose one: Mixed, Mostly city, Mostly highway |
| Distance | Units: mi, km, m, nmi |
| Gas price | Units: /US gal, /L, /UK gal |
| People sharing | A number |
What each result means
- Gas used = [Distance]÷[Fuel economy used]
- Cost of the trip = [Gas used]×[Gas price]
- Cost per person = [Cost of the trip]÷[People sharing]
Example values
How the main result changes when Fuel economy changes and everything else stays at the example values above:
| Fuel economy (if Other) (mpg (US)) | Cost of the trip |
|---|---|
| 12.5 | 21.87 |
| 18.75 | 21.87 |
| 25 | 21.87 |
| 31.25 | 21.87 |
| 37.5 | 21.87 |
| 50 | 21.87 |
Formula
Fuel economy = car rating × trip factor (city 0.85, highway 1.15)Gas used = distance ÷ fuel economyCost = gas used × price; per person = cost ÷ peopleWorked example
Inputs — Car: Toyota Camry (≈ 32 mpg); Fuel economy (if Other): 25 mpg (US); Trip type: Mixed; Distance: 200 mi; Gas price: $3.5 /US gal; People sharing: 1.
Results — Fuel economy used = 32 mpg (US); Gas used = 6.25 US gal; Cost of the trip = $21.87; Cost per person = $21.87.
Frequently asked questions
How much gas will a 200-mile trip use?
At 32 mpg about 6.25 gallons – roughly $22 at $3.50/gal.
Why is my car's real mpg lower than the rating?
Short trips, cold weather, aggressive driving, heavy loads and under-inflated tyres all reduce economy.
How accurate are the model figures?
They are approximate EPA combined ratings for recent models; enter your own measured mpg for best accuracy.
What formula does the Gas Calculator use?
Fuel economy = car rating × trip factor (city 0.85, highway 1.15).