How route distance and fuel economy become liters and cost
A trip budget starts with fuel volume, not price alone. This calculator translates your route and vehicle's economy convention to liters before applying the price you enter, with no claim about a live pump rate.
Fuel-economy labels point in opposite directions. A lower L/100 km figure means less fuel for the same route; a higher km/L or US mpg figure means more distance per volume. Treating those numbers as interchangeable can reverse a cost comparison. This calculator converts the selected convention to liters consumed before it applies the entered price.
Route checkpoints connect distance to fuel volume and entered price. The engine changes formula when the vehicle uses L/100 km, km/L or US mpg instead of treating those labels as interchangeable.
Why distance, economy convention and price unit move the trip cost
Three numbers and three unit choices feed one chain: distance to liters, then liters to money. A wrong unit choice changes the answer more than a slightly wrong number does.
- Trip distance and unit
- Enter the whole route you want to budget; for a return trip, double the one-way distance. Cost scales in direct proportion, so 480 km costs exactly twice the example's 28.8. Choosing miles when your figure is in kilometers multiplies the route by 1.609344, turning the example's 19.2 L into about 30.9 L.
- Fuel economy convention
- L/100 km, km/L and US mpg each use a different formula, so the number means nothing without its label. The example's 8 read as L/100 km needs 19.2 L; read as 8 km/L it needs 30 L, and as 8 US mpg about 70.6 L. Copy the unit printed beside the figure on your vehicle's display or manual.
- Fuel price
- This is the pump price in your own currency, with no live feed behind it. Cost moves one-for-one with price: raising the example's 1.5 by 10% to 1.65 lifts the trip from 28.8 to 31.68. A price of 0 is accepted if you only want the fuel volume.
- Price per liter or US gallon
- A price quoted per US gallon is divided by 3.785411784 before use. Marking a per-liter price as per gallon by mistake turns the example's 1.5 per liter into about 0.40 and the trip cost from 28.8 into 7.61. Prices per Imperial gallon are not supported.
- Constant-rate assumption
- Economy and price are held fixed for the whole route, which is why the halfway checkpoint always shows exactly half the fuel and cost. Mixed city and highway driving can move real consumption well away from one average, so enter the economy you actually see on similar trips rather than a brochure figure.
Steps
- Enter trip distance and its kilometer or mile unit.
- Enter your vehicle's fuel economy and choose the exact convention printed beside that value.
- Enter a current price from your own source, mark liter or US gallon, and compare fuel needed with estimated trip cost.
Reading tip: The route checkpoints show cumulative distance, estimated liters and estimated cost at start, halfway and destination, assuming the same economy and price throughout.
Trip-budget questions this fuel estimate covers
Budget a trip
Estimate route fuel volume and spending from a distance and your own pump-price input.
Compare economy labels
Handle L/100 km, km/L and US mpg with the appropriate consumption formula.
Check price units
Convert a price quoted per US gallon to a per-liter basis before estimating cost.
Explore a longer route
See how extra distance changes cumulative fuel and cost when the entered economy stays fixed.
How the calculation works
- km / miles
- The route length expressed in the distance basis required by the chosen economy convention.
- L/100 km / km/L / US mpg
- Alternative consumption conventions; choose one rather than multiplying their displayed values together.
- 3.785411784
- Exact number of liters in the US liquid gallon used for the mpg and per-gallon price options.
- price/L
- User-entered fuel price converted to a per-liter basis in the same currency.
Fuel economy and price are held constant for the scenario; no live price, traffic or route model is included.
What every part means
- km / miles
- The route length expressed in the distance basis required by the chosen economy convention.
- L/100 km / km/L / US mpg
- Alternative consumption conventions; choose one rather than multiplying their displayed values together.
- 3.785411784
- Exact number of liters in the US liquid gallon used for the mpg and per-gallon price options.
- price/L
- User-entered fuel price converted to a per-liter basis in the same currency.
Calculate it step by step
Miles use the defined international mile; US mpg also uses miles directly.
Choose exactly one branch matching the vehicle's displayed economy convention.
The US liquid gallon definition applies both to mpg fuel volume and gallon-priced fuel.
Decimal arithmetic keeps the kilometer, mile and gallon factors unrounded through the estimate. A zero-distance trip produces zero modeled fuel cost without dividing by distance for its cost-per-kilometer fact.
See how Calculation Guide tests examples and handles calculation limits.
See it in practice
- Trip distance
- 240
- Distance unit
- Kilometers
- Vehicle fuel economy
- 8
- Fuel economy unit
- Liters per 100 kilometers
- Entered fuel price
- 1.5 currency units
- Price is per
- Liter
Distance 240 km, economy 8 L/100 km, entered price 1.5 per liter: fuel = 240×8/100 = 19.2 L; cost = 19.2×1.5 = 28.8 currency units.
- Trip distance in kilometers240 km
- Estimated fuel needed19.2 L
Interpretation & limitations
How to read your result
A 240 km route at 8 L/100 km needs 19.2 L. At 1.5 currency units per liter, the model gives 28.8. Use this as a budget scenario, not an exact fuel receipt.
Where this estimate stops
Vehicle economy may differ between city and highway driving, altitude, temperature, traffic and load. This tool has no current price feed, no tolls and no currency conversion; enter a price that fits your route and date.
Frequently asked questions
01Is 8 L/100 km the same as 8 km/L?
No. L/100 km measures fuel used for a fixed distance; km/L measures distance per liter. The calculator uses different formulas for each convention.
02Does this show today's fuel price?
No. It uses only the price you type. Local prices and currencies vary, and the result has no live rate feed.
03Does US mpg use an Imperial gallon?
No. The US mpg option uses the US liquid gallon, exactly 3.785411784 liters. Imperial mpg is a different measure and is not offered.
04Can the route distance be in miles while price is per liter?
Yes. Distance and fuel-price units are selected independently; the calculator normalizes both before multiplying.
05Why can a more efficient vehicle show lower cost?
At a fixed route and price, consuming fewer liters lowers the modeled fuel charge directly.
06Is an actual road trip likely to cost exactly this amount?
No. The engine holds fuel economy and price constant, while real conditions can change both.