Fuel Consumption Calculator - MPG and L/100 km

A fuel consumption calculator turns the distance you drove and the fuel you used into practical fuel-economy measures. Use it after a fill-up, after a delivery route, before a road trip, or when you want to compare two vehicles using the same units. It works for miles with U.S. gallons and for kilometers with liters, so the result can match the way your odometer and receipt are written.

• • After-refill mileage check: Reset the trip meter, drive normally, refill, and enter the distance plus fuel added to measure the last tank.
• • Route comparison: Compare fuel use for commuting, delivery, towing, city driving, and highway driving without mixing MPG and metric units.
• • Trip planning: Use the range estimate to judge whether the fuel on hand is enough for the next segment.
• • Vehicle tracking: Record repeated calculations to spot changes caused by tires, loads, weather, maintenance, or driving style.

The calculator reports both efficiency and consumption. MPG and km/L answer how far the vehicle travels per fuel unit. Gallons per 100 miles and L/100 km answer how much fuel the vehicle uses for a fixed distance. Those two views are useful in different situations, so the page shows both instead of forcing one convention.

Use a measured fill-up when you need a real-world result. Rated fuel economy is useful for shopping, but your own log can be more useful for budgets, route planning, and noticing a sudden change in fuel use.

After you measure consumption, Fuel Cost Calculator can turn the same route and a pump price into a trip budget.

The math starts with one direct ratio, then converts that result into the common U.S. and metric fuel-consumption formats.

• Distance: The measured trip distance, converted internally to both miles and kilometers.
• Fuel used: The amount of fuel consumed over that distance, converted internally to U.S. gallons and liters.
• MPG: Miles traveled per U.S. gallon. Higher MPG means less fuel is used for the same U.S. route.
• L/100 km: Liters used per 100 kilometers. Lower L/100 km means less fuel is used for the same metric route.
• Fuel on hand: The optional remaining fuel amount used to estimate miles and kilometers of range.

For metric entries, the calculator converts kilometers and liters before calculating the same outputs. A 450 km trip that uses 36 liters equals 8.00 L/100 km, 12.50 km/L, and about 29.40 MPG.

Gallons per 100 miles is included because it is a consumption measure. If one vehicle uses 3.0 gal/100 mi and another uses 4.0 gal/100 mi, the difference is one gallon for every 100 miles driven.

According to NIST, fuel economy in miles per U.S. gallon converts to L/100 km by dividing 235.215 by the MPG value.

According to U.S. EPA, MPG equals miles traveled divided by gallons used, while gallons per 100 miles expresses fuel used over a fixed 100-mile distance.

When you only need to switch between MPG, L/100 km, km/L, and related units, Fuel Economy Converter handles the unit-only workflow.

Fuel-consumption numbers are easy to misread because some go up when efficiency improves and others go down.

Do not average MPG values by adding them and dividing by the number of trips unless the trips used the same amount of fuel. For a combined result, add all distance, add all fuel, then divide total distance by total fuel.

Consumption units help when comparing savings. Improving from 15 to 20 MPG saves more fuel over 100 miles than improving from 35 to 40 MPG, even though both changes look like five MPG.

For a broader route fuel estimate that starts from distance, price, and expected mileage, Gas Calculator covers the planning side.

For the cleanest result, measure one complete fuel interval and keep the units consistent with your receipt or pump display.

1. 1 Measure distance: Reset the trip meter after filling the tank, or subtract the starting odometer reading from the ending reading.
2. 2 Record fuel used: Use the amount added at the next refill when the tank is filled to a similar level.
3. 3 Choose units: Select miles or kilometers for distance, then U.S. gallons or liters for the fuel entries.
4. 4 Add fuel on hand: Enter the fuel currently available when you want a range estimate for the next leg.
5. 5 Read both views: Use MPG or km/L for efficiency language, and use gallons per 100 miles or L/100 km when comparing fuel used over a route.

If your commute log shows 186 miles and the refill takes 6.2 gallons, the calculator reports 30 MPG. If fuel on hand is 8 gallons, the range estimate is about 240 miles before any reserve allowance.

If your next question is how much the refill itself will cost at the pump, Fuel Pump Calculator uses fuel amount and price directly.

A small fuel log can answer practical questions that a dashboard average may hide.

• • Budget a recurring route: Use measured consumption with a fuel-price tool to estimate weekly commute, delivery, or school-run cost.
• • Compare driving conditions: Separate city, highway, towing, winter, and loaded trips to see which conditions change fuel use.
• • Plan refueling stops: Use the range output as a starting point, then keep a reserve for traffic, grade, weather, and detours.
• • Watch maintenance effects: A sudden change in repeated logs can point to tire pressure, alignment, brake drag, sensor issues, or load changes.
• • Compare vehicles plainly: Use gallons per 100 miles or L/100 km when two MPG values are close but annual mileage is high.

The result is most useful when you record the same method each time. A single short trip can be skewed by warm-up time, traffic, idle time, or one unusual load.

For budgeting, pair the consumption result with fuel price and annual distance. For maintenance, compare several similar trips before assuming one reading shows a problem. A fuel consumption calculator is strongest when it supports a habit of consistent logs rather than a one-time guess.

For monthly ownership planning, Car Budget Calculator can combine fuel with payment, insurance, maintenance, and other vehicle costs.

Real-world fuel use changes with the vehicle, driver, route, and measurement method.

• • This calculator estimates consumption from your entered distance and fuel. It does not diagnose vehicle faults or replace manufacturer service guidance.
• • Range is a planning estimate, not a reserve policy. Keep extra fuel margin for hills, traffic, weather, road closures, and fuel-station spacing.
• • Dashboard averages and official ratings may use different measurement methods than a manual fill-up log.

Official fuel-economy ratings are useful for comparing vehicles under defined procedures. A personal fuel log is useful for your own routes because it includes how and where the vehicle is actually driven.

When a result looks unusual, repeat the measurement over another full tank before acting on it. Treat the fuel consumption calculator result as a measurement note, then check simple items such as tire pressure and load if several similar logs change sharply.

According to U.S. EPA fuel economy testing, the agency defines the methods used to calculate fuel economy estimates shown on new-car window stickers.

When repeated logs give you a stable average, Annual Fuel Cost Calculator can project that consumption across yearly mileage.