Fuel Cost Calculator — Trip Cost
Calculate trip fuel cost from distance, fuel efficiency, and price per litre or gallon. Supports km/L, L/100km, mpg, and both metric and imperial units.
What Is the Fuel Cost Calculator — Trip Cost?
The fuel cost calculator estimates how much fuel a trip will consume and what it will cost. It supports multiple efficiency units: litres per 100 km (L/100km) used in most of the world, kilometres per litre (km/L) common in South and Southeast Asia, and miles per gallon (mpg) used in the US and UK. Fuel price can be entered per litre, per gallon, or any consistent unit.
Formula
How to Use
Select your efficiency unit system, enter the trip distance, your vehicle's fuel efficiency, and the current fuel price. The calculator outputs total fuel needed and total cost. Use the round-trip toggle to double the distance automatically.
Example Calculation
Trip: 400 km, efficiency 7.5 L/100km, fuel price $1.85/L → Fuel used = 400 × 7.5 / 100 = 30 L → Cost = 30 × 1.85 = $55.50.
Understanding Fuel Cost — Trip Cost
Fuel costs are one of the largest variable expenses for vehicle owners. Understanding the true per-kilometre or per-mile fuel cost helps with budgeting road trips, comparing vehicles before purchase, and evaluating whether a more fuel-efficient car is worth the premium.
Fuel efficiency varies with speed, load, tyre pressure, air conditioning use, and driving behaviour. Aggressive acceleration and braking can reduce efficiency by 15–30%. Maintaining steady highway speeds near a vehicle's most-efficient operating point (typically 80–100 km/h for most cars) minimises fuel consumption per kilometre.
The L/100km unit is intuitive for cost calculations because a lower number always means better efficiency. The km/L and mpg units are inverse — higher is better — which can be counterintuitive when comparing improvements (going from 8 to 9 mpg saves more fuel per km than going from 48 to 49 mpg, even though both are 1 unit improvements).
Frequently Asked Questions
How do I convert between L/100km and mpg?
Use: mpg (US) = 235.215 / (L/100km). For example, 8 L/100km = 235.215/8 ≈ 29.4 mpg (US). UK mpg uses Imperial gallons: mpg (UK) = 282.48 / (L/100km).
My car shows km/L not L/100km — what do I enter?
Switch the efficiency unit to km/L. The calculator handles the conversion internally. For example, 13 km/L = 100/13 ≈ 7.7 L/100km.
Does fuel efficiency change on motorways vs city driving?
Yes significantly. Most vehicles consume 20–40% more fuel in stop-start city driving than at steady highway speeds. Your car manual usually shows both city and highway ratings; use a weighted average based on your expected driving mix.
Can I use this for electric vehicle energy cost?
Yes — enter your electric vehicle's kWh/100km (or miles/kWh) as the efficiency figure and cost per kWh as the price. The formula is identical; only the unit label changes.
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