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Fuel Cost Calculator

Enter trip distance, your car's MPG and the fuel price.

Short answer

Cost = (distance ÷ MPG) × 4.546 × (price per litre ÷ 100). The 4.546 converts gallons (UK) to litres.

Trip

miles
MPG
p/litre

Fill in the fields above to see your result instantly.

How it works

UK MPG uses the imperial gallon (4.546 L). Convert miles → gallons → litres → cost using your pence-per-litre price.

Worked example

100 miles at 45 MPG, fuel 150p/L: 100/45 = 2.22 gal × 4.546 = 10.10 L × £1.50 = £15.15.

Who should use this

  • Drivers planning a long trip
  • Mileage expense claims
  • Comparing two cars' running cost

Common mistakes

  • ×Using US MPG (smaller gallon) — UK MPG is 20% bigger
  • ×Forgetting a round trip

Frequently asked questions

Why isn't my real MPG matching the brochure?

Manufacturer MPG is from a lab test (WLTP). Real-world is usually 10–25% lower.

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