Fuel Cost Calculator
Calculate the fuel cost of any journey based on distance, fuel price and your vehicle's MPG or L/100km.
By Konstantin Iakovlev · Founder, Calks.uk
Last updated: · Verified against HMRC and GOV.UK 2026/27 rates
Fuel Cost
£15.34
Litres Needed
11.4L
Cost per Mile
15.3p
Distance
100 mi
Disclaimer
This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.
How It Works
Fuel cost is calculated by dividing the journey distance by your vehicle's fuel efficiency, then multiplying by the price per litre. UK fuel efficiency is commonly quoted in miles per gallon (MPG) but fuel is sold in litres, so a conversion is needed: 1 UK gallon = 4.546 litres.
The HMRC approved mileage allowance for business use is 45p per mile for the first 10,000 miles and 25p per mile thereafter. This is designed to cover fuel, insurance, depreciation and wear — not just fuel costs. If your employer pays less than these rates, you can claim tax relief on the difference.
This calculator lets you enter distance, fuel efficiency and fuel price to estimate the cost of any journey. It also shows the equivalent HMRC mileage allowance for comparison.
Cost-per-mile formula explained. Cost per mile = (fuel price per litre × 4.546) ÷ mpg. The 4.546 converts gallons (which mpg uses) to litres (which UK fuel sells in). Example: £1.45/litre × 4.546 = £6.59/gallon. At 40 mpg: £6.59 ÷ 40 = 16.5p/mile. At 50 mpg: 13.2p/mile. At 30 mpg: 22p/mile. For trip planning: multiply by total miles for fuel cost only (excludes wear, tax, insurance, depreciation).
UK fuel price breakdown — where your money goes. 2026 typical pump prices: ~£1.45/litre petrol, ~£1.50/litre diesel. Components: Fuel Duty 52.95p/litre (frozen since 2011); VAT 20% on (duty + base) ~25p/litre; wholesale fuel 50-55p; retailer margin 7-10p. Total tax: 75-80p/litre = 50-55% of pump price. UK has 2nd-highest fuel taxes in Europe (Netherlands marginally higher). Diesel and petrol duty rates have been identical since 2011 — diesel pump premium reflects refining cost only.
HMRC mileage rates and business travel. Approved Mileage Allowance Payments (AMAP) 2026/27: 45p/mile for first 10,000 business miles; 25p/mile thereafter. Motorcycles: 24p/mile any distance. Bicycles: 20p/mile. Passengers: extra 5p/mile per passenger. These rates cover fuel + wear + tax + insurance + depreciation — not just fuel. At current £1.45 petrol prices, the 45p rate is roughly 2-3× actual fuel cost. Self-employed: claim AMAP via Self Assessment. Employees: claim difference if employer pays less than AMAP.
EV vs petrol cost-per-mile. Home charging (off-peak 8p/kWh): typical EV 4 miles/kWh = 2p/mile fuel cost. Public rapid charging (60-80p/kWh): 15-20p/mile — comparable to petrol. Workplace charging often free or subsidised. Petrol at 45 mpg, £1.45/litre: 14.7p/mile fuel. EV winter range drops 20-30% (heater); summer near-rated range. Total cost of ownership: EV typically cheaper from year 4-5 onwards (lower fuel + maintenance, no road tax until 2025, BIK 3% 2025/26 rising 1pp/year). Salary sacrifice EV schemes can save 30-50% of monthly cost for higher-rate taxpayers.
Reduce fuel consumption — proven techniques. Drive smoothly: aggressive acceleration uses 30-40% more fuel. Maintain tyres at correct pressure: under-inflated by 0.5 bar costs 5-10% fuel economy. Remove roof racks/boxes when unused: aerodynamic drag costs 10-25% on motorways. Don't idle: cars don't need warm-up time; idling for 2+ minutes wastes more fuel than restarting. Use cruise control on motorways (saves 5-10%). Plan routes to avoid stop-start traffic. Check engine: faulty oxygen sensor can cost 40% efficiency. Average UK family saving £200-£400/year from these combined.
Example: 200-mile round trip, 40 MPG, fuel at £1.40/litre
- Fuel needed: 200 ÷ 40 = 5 gallons = 22.73 litres
- Fuel cost: 22.73 × £1.40 = £31.82
- HMRC mileage: 200 × 45p = £90.00
- Difference (covers wear, insurance etc.): £58.18
Frequently Asked Questions
- Cost per mile formula.
- Cost per mile = (fuel price ÷ mpg) × 4.546 (litres per gallon). At £1.45/litre × 4.546 = £6.59/gallon. With 40 mpg: 16.5p/mile. At 50 mpg: 13.2p/mile. At 30 mpg: 22p/mile. For business: HMRC pays 45p/mile first 10k (then 25p) covering fuel + wear + tax + insurance. At current fuel prices, the 45p rate is roughly 2× actual fuel cost — covers other running expenses too.
- UK fuel price breakdown.
- 2026 averages: ~£1.45/litre petrol, ~£1.50/litre diesel. Breakdown: Fuel Duty 52.95p/litre (frozen since 2011), VAT 20% on (duty + base price) ~25p/litre, wholesale fuel cost 50-55p, retailer margin 7-10p. Total tax: ~75-80p per litre (50-55% of pump price). UK has among Europe's highest fuel taxes — only Netherlands consistently higher. Petrol and diesel duty rates are identical since 2011.
- How to reduce fuel costs.
- (1) Switch to an EV — home charging at 8p/kWh = 2p/mile (vs 16p petrol); (2) Drive smoothly — aggressive acceleration uses 30-40% more fuel; (3) Maintain tyres at correct pressure (under-inflated = 5-10% more fuel); (4) Remove roof racks and unnecessary weight; (5) Air conditioning at low speeds uses ~10% more fuel; (6) Plan combined trips — cold engines use 50% more fuel; (7) Use supermarket fuel (Asda, Tesco) — often 2-5p/litre cheaper than branded stations.