🚗 Auto Updated2026-07-19
Fuel Cost Calculator.
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Quick answer
Trip cost = (distance ÷ efficiency) × fuel price. A 100-mile trip at 30 MPG and $3.50/gal uses 3.33 gallons = $11.67 one way ($23.33 round trip), about $0.117 per mile. Enter your numbers below.
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Fuel Cost Calculator
Trip type
One-way trip cost
$11.67
= 3.33 gallons · $0.117/mile
$11.67
One way
$23.33
Round trip
✨ Live · Fuel used = distance ÷ efficiency; cost = fuel used × price. Round trip doubles the distance. US gallon = 3.785 L.
📊 Quick reference
Fuel cost by trip distance.
At 30 MPG and $3.50 per US gallon, one way.
| Distance | Fuel used (gal) | Trip cost |
|---|---|---|
| 50 miles | 1.67 | $5.83 |
| 100 miles | 3.33 | $11.67 |
| 200 miles | 6.67 | $23.33 |
| 300 miles | 10.00 | $35.00 |
| 500 miles | 16.67 | $58.33 |
❓ FAQ
Common questions.
How do I calculate fuel cost for a trip?
Divide the trip distance by your vehicle's fuel efficiency to get the fuel used, then multiply by the fuel price. For example, a 300-mile trip in a car that does 30 MPG uses 300 ÷ 30 = 10 gallons; at $3.50 per gallon that is 10 × $3.50 = $35.00. In metric the same idea applies: distance in km ÷ efficiency in km/L gives litres, multiplied by the price per litre. Real-world mileage is usually 5–15% worse than the sticker figure, so budget a little extra for hills, headwinds, and city stop-and-go.
How much does a 500-mile road trip cost in gas?
At 30 MPG and $3.50 per gallon, a 500-mile trip uses 500 ÷ 30 = 16.67 gallons, which costs 16.67 × $3.50 = $58.33 one way. If it is a round trip you cover 1,000 miles and burn 33.33 gallons, so the fuel bill roughly doubles to $116.67. A more efficient 40 MPG car would use only 12.5 gallons one way ($43.75), while a 20 MPG SUV would need 25 gallons ($87.50). Efficiency is the single biggest lever on trip cost.
How do I work out the cost per mile of driving?
Cost per mile is simply the fuel price divided by the miles per gallon: $3.50 ÷ 30 MPG = $0.117 per mile. Over a 100-mile trip that is about $11.67 in fuel. This "cents per mile" figure is handy for comparing vehicles, estimating commuting costs, or working out mileage reimbursement. Note it only covers fuel. Total running cost per mile also includes depreciation, insurance, tyres, and maintenance, which often add more than the fuel itself.
How do I calculate fuel cost in litres and kilometres?
Switch the calculator to Metric and enter distance in kilometres, efficiency in km per litre, and price per litre. Fuel used = distance ÷ efficiency, and cost = fuel used × price. For example, a 480 km drive in a car doing 12 km/L uses 480 ÷ 12 = 40 litres; at $1.50 per litre that is 40 × $1.50 = $60.00. If your economy is quoted as L/100km instead, divide 100 by that number to get km/L (e.g. 8 L/100km = 12.5 km/L).
Does a round trip just double the fuel cost?
Yes. A round trip covers the distance twice, so both the fuel used and the cost double, while the cost per mile stays the same. A 100-mile one-way trip at 30 MPG and $3.50/gallon costs $11.67; the 200-mile round trip costs $23.33. Toggle the round-trip switch and the calculator shows both figures side by side, so you can see the one-way and there-and-back totals at once when planning a commute or weekend drive.