Fuel Economy
Fuel Economy — runs in your browser. Inputs are not stored.
Fuel economy calculator
Enter values, then press Calculate.
How to use
- Enter distance (km) for the same stretch, whether fill-to-fill or trip. Default example is 400.
- Enter fuel (L) put in on that stretch. Default is 30.
- Press Calculate to see economy (km/L) and L/100km.
- If the dash trip and pump volume disagree a lot, remeasure both numbers. MPG is not in this version.
- EV kWh efficiency is not this formula—the energy unit is not liters.
Key concepts
The fuel economy calculator converts real economy, km/L, and European-style L/100km. km/L = distance ÷ fuel; L/100km = (fuel ÷ distance) × 100. Both Korean official notation and L/100km sit on one screen. There is no MPG and no EV efficiency. Higher km/L and lower L/100km mean better efficiency. If the trip computer disagrees with calculated economy, a missed fill-up or unreset trip is common. Numbers are calculated only on this device.
Fill-to-fill is not required if km and L share the same stretch. Math is local. Gauge vs pump error wobbles the number. EV kWh efficiency is not the L-field formula. A missed fill-up makes economy look unrealistically good. MPG conversion is not in this version.
Example
400 km on 30 L is 13.33 km/L and 7.50 L/100km. 500 km on 25 L is 20 km/L and 5.00 L/100km. More fuel for the same distance worsens km/L. 320 km on 28 L is about 11.43 km/L and 8.75 L/100km. Better economy makes L/100km smaller. 180 km on 15 L is 12 km/L and 8.33 L/100km. The same distance on 12 L is 15 km/L.
Related: Fuel cost calculator · Calorie calculator (BMR·TDEE) · Water intake calculator
Frequently asked questions
Does economy calculation require fill-to-fill only?
Any km and L on the same basis work. Fill-to-fill is not required if the stretch matches.
Are economy numbers sent to a server?
No. Division runs only on this device, in the browser.
Is MPG (miles) economy shown?
This version is km/L and L/100km. There is no miles-per-gallon conversion.
What if trip economy and calculated economy differ?
Check trip and pump measurement error. Skipping a fill-up also skews it and can make economy look unrealistically good. Suspect gauge error.
Can I use this for EV efficiency?
kWh needs a separate conversion. The L field is fuel volume. Calculate EVs separately with kWh and km.
Is a smaller L/100km better?
Yes. Less fuel per 100 km is more efficient. Larger km/L is also better.
Last reviewed: 2026-09-04