Eight markets

Know what a journey really costs.

Fuel, charging and efficiency calculators that make the unit system explicit — including the UK/US MPG trap. No signup, no live-price claims, and every formula is shown.

Calculate trip fuel cost Convert MPG and L/100 km

Your inputs stay in your browser. Market prices and regulations are not hardcoded.

The same number, different gallons

“40 MPG” does not describe the same fuel consumption in the UK and the US.

40 MPG UK

7.06 L/100 km

imperial gallon = 4.54609 L

40 MPG US

5.88 L/100 km

US gallon = 3.785411784 L

The UK figure is about 20% higher in L/100 km. Using the wrong gallon changes the answer.

Read why UK and US MPG differ

The initial toolkit

Five tools, built around real decisions

Each calculator uses tested formulas, explicit units and sensible inputs. They are deliberately not one page per keyword.

View all tools

UnitsUniversal

Fuel efficiency converter

Convert between L/100 km, MPG UK, MPG US and km/L, and between MPGe, mi/kWh and kWh/100 km.

Open calculator

Fuel8 markets

Fuel cost calculator

Estimate trip fuel use, total cost and cost per mile or kilometre with UK, US, European, Swiss and Asia-Pacific units.

Open calculator

EV8 markets

EV charging cost calculator

Calculate home or public charging cost from energy added, price per kWh, charging losses and session fees in eight markets.

Open calculator

EV8 markets

Petrol or gas vs EV cost calculator

Compare annual running costs on the same distance basis across eight markets, with an optional purchase-price break-even estimate.

Open calculator

UnitsUniversal

kW ↔ PS ↔ hp converter

Convert kilowatts, metric horsepower (PS) and mechanical horsepower (hp/bhp) in every direction.

Open calculator

Built for eight markets

One set of tools, eight sets of conventions

United Kingdom

Miles, MPG (UK) and pence per litre

UK fuel is sold in litres but economy is usually quoted in imperial MPG. The calculators bridge that gap explicitly.

United States

Miles, MPG (US) and dollars per gallon

US gallons are smaller than imperial gallons. EV efficiency is also available as MPGe, mi/kWh and kWh/100 mi.

Europe

Kilometres, L/100 km and euros per litre

Euro-area defaults use kilometres, litres and litres per 100 km. Switch markets without silently reusing the wrong unit.

Switzerland

Kilometres, L/100 km and Swiss francs per litre

Swiss road distances and fuel economy use metric units, but fuel and charging prices are in CHF rather than EUR.

Japan

Kilometres, km/L and yen per litre

Japanese fuel economy is usually quoted in kilometres per litre.

India

Kilometres, km/L and rupees per litre

Indian road distances and fuel economy use kilometres and km/L.

South Korea

Kilometres, km/L and won per litre

South Korean road distances and fuel economy use kilometres and km/L.

Australia

Kilometres, L/100 km and Australian dollars per litre

Australian fuel economy uses litres per 100 kilometres.

Prices are not live

Fuel and electricity prices change by region, grade and tariff. These tools ask you for the price you actually pay. They do not publish a national price or claim real-time coverage.

What is different

Transparent by default

These are the differences we can defend without unverified market data.

Unit system stated

UK MPG, US MPG and L/100 km are never treated as interchangeable. Each conversion says which gallon it uses.

Formula shown

The calculation is visible below each tool and covered by automated tests, including zero and boundary cases.

No signup or data trail

Calculations run in the browser. We do not send journey details or price inputs to an analytics service.

Changing data kept out

No invented prices, tolls, vignettes or tax rates. Time-sensitive pages will only be added after official verification.

Guides

Understand the number, not just the output

All 29 guides →

Why UK and US MPG are different

The imperial and US gallons are not the same. Here is the exact conversion and why the same car can appear more efficient in Britain.

How trip fuel cost is calculated

The formulas behind the fuel cost calculator, including UK pence-per-litre pricing, US gallons and European litres per 100 km.

MPGe, mi/kWh and kWh/100 km explained

How EPA MPGe relates to real electric consumption, and how to compare it without confusing energy with liquid fuel.

Common questions

Direct answers

Is 40 MPG good?

It depends on the gallon. In the UK, 40 MPG is about 7.06 L/100 km. In the US, 40 MPG is about 5.88 L/100 km. That is a meaningful difference, so a published MPG figure needs its system stated. Vehicle size, fuel type and driving conditions matter just as much as the number.

Why do UK and US MPG differ?

An imperial gallon is 4.54609 litres and a US gallon is 3.785411784 litres. A mile is the same, so the same car returns a different MPG number on each side of the Atlantic. The ratio is about 1.20095.

Does this site use live fuel prices?

No. Fuel and electricity prices are user inputs. Live national or local prices require a real, maintained data source; we do not simulate one.

Are the calculations a guarantee of cost?

No. They are estimates based on the inputs you provide. Real consumption varies with driving style, weather, load, tyre pressure and route. Petrol-versus-EV comparisons exclude maintenance, insurance, tax and depreciation unless you add a price gap yourself.

Page last reviewed: 27 October 2026. Formulas are covered by automated tests. Prices are inputs, not live data.

Roadmap, not filler

Vignettes, tolls and tax pages are being held back

Those topics need dated, official figures and a maintenance schedule. Publishing a price without verification would be worse than publishing nothing. The calculators that are live rely on your inputs and tested unit conversions.

Read the methodology and deferred-work list See the corrections log