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Enter how far you drove and how much fuel you used to get US MPG, litres per 100 km, and km per litre in one run.
Quick answer: Fuel Efficiency Calculator
Divide distance by fuel in consistent units, then mirror L/100 km and US MPG with the standard gallon conversion.
Example: 320 miles on 9.2 gal → ~34.8 MPG → ~6.8 L/100 km headline equivalents.
Calculations follow the documented formula on this page; rounding and input units can change the last digit-treat outputs as educational estimates unless you reconcile with source systems.
* This is an estimate. Actual amounts may vary slightly based on input assumptions.
Trip odometer plus pump litres or gallons beats dashboard averages when the ECU lies at short trips.
Enter how far you drove and how much fuel you used to get US MPG, litres per 100 km, and km per litre in one run.
Inputs on this page: Input system, Distance driven, Fuel used. Assumptions stay visible so you can reproduce the figure elsewhere.
Long-form walkthroughs that pair well with this calculator. When you need narrative context beyond the live fields, start here and return to the tool to plug in your own numbers.
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Read guide →People who care about fuel efficiency calculator use Fuel Efficiency Calculator as a planning sandbox: UK imperial gallons need the dedicated MPG converter - don’t mix with US mode here.
Continue in the Calculators category hub, the Utility tools collection, or the glossary. Related calculators in this session: KM to Miles Converter, Gas Cost Calculator Road Trip, EV vs Petrol Cost Calculator, Car Running Cost Calculator, MPG to L/100km Converter, Percentage Calculator.
The Formula
US MPG = miles ÷ gallons; L/100 km = (litres ÷ km)×100; convert with 235.214583 factor for US MPG ↔ L/100 km| This tool | US MPG = miles ÷ gallons; L/100 km = (litres ÷ km)×100; convert with 235.214583 factor for US MPG ↔ L/100 km |
|---|---|
| Related intent: fuel efficiency calculator | See paired tools for fuel efficiency calculator-each page documents its own core relationship next to the live form. |
| Related intent: mpg calculator from trip | See paired tools for mpg calculator from trip-each page documents its own core relationship next to the live form. |
Core relationship for Fuel Efficiency Calculator:
US MPG = miles ÷ gallons; L/100 km = (litres ÷ km)×100; convert with 235.214583 factor for US MPG ↔ L/100 km
Worked check: 320 miles on 9.2 gal → ~34.8 MPG → ~6.8 L/100 km headline equivalents.
Keep the same assumptions and open a neighbor calculator when your question branches: KM to Miles Converter, Gas Cost Calculator Road Trip, EV vs Petrol Cost Calculator, Car Running Cost Calculator. Each page documents its own formula beside the fields.
Learning links: Methodology · Editorial policy · Glossary
320 miles on 9.2 gal → ~34.8 MPG → ~6.8 L/100 km headline equivalents.
Re-enter the same numbers in the calculator above to confirm the page math matches the interactive result.
People who care about fuel efficiency calculator use Fuel Efficiency Calculator as a planning sandbox: UK imperial gallons need the dedicated MPG converter - don’t mix with US mode here.
Instant response
Run Fuel Efficiency Calculator in the browser and read the breakdown beside the form.
Transparent formula
The formula and worked example on this page match what the calculator uses.
Privacy friendly
No account required; inputs stay in your session unless you choose to share them.
Cross-device ready
Layout works on mobile, tablet, and desktop for the same field labels.
Official references for context. Calculator outputs are planning estimates—confirm material decisions with the primary authority or a qualified professional. See our methodology and editorial policy.
Reviewed July 18, 2026 · Content stamp 2026-07-18
Click a question to expand the answer.
No. This is from your actual distance and fuel; your driving style and conditions differ from lab tests.
US MPG to L/100 km uses 235.214583 ÷ MPG (constant for US liquid gallons).
This tool uses US gallons in US mode. For UK MPG, use the MPG/L/100km converter tool.
Best accuracy comes from full tank to full tank over a known odometer distance.
Yes. The math is the same; only energy content per litre differs from petrol slightly in strict engineering models.
Divide distance by fuel in consistent units, then mirror L/100 km and US MPG with the standard gallon conversion.
320 miles on 9.2 gal → ~34.8 MPG → ~6.8 L/100 km headline equivalents.
UK imperial gallons need the dedicated MPG converter - don’t mix with US mode here. Short winter warmups tank efficiency; log summer and winter separately. EV kWh/100 km belongs in running-cost or EV tools, not this fuel volume path.
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Reviewed by Toollabz Editorial
Product editor | Last reviewed July 18, 2026
See methodology and editorial policy.