Example 1 — basic fill-up
- Mode: measure
- 250 miles
- 10 gallons
25 mpg · 4.00 gal / 100 mi
What mpg is 250 mi and 10 gal? 250÷10 = 25 mpg (4.00 gal/100 mi).
Fuel Consumption Calculator
In measure mode, enter the miles you drove and the gallons you added at the pump. The calculator divides miles by gallons to give tank mpg — real fill-up economy, not the EPA window sticker. The result also shows gallons per 100 miles. With the metric header the same stretch appears as L/100 km.
Results
Enter distance and fuel added, or distance and known economy. The result appears here.
With the US header, mpg uses the US gallon (about 3.785 L), not the imperial gallon. Measure economy, then use the result in trip fuel cost. Annual upkeep is on annual running cost, and full ownership cost is on car TCO.
How the results are calculated
Distance250 mi
Fuel10 gal
mpg25
In measure mode, economy is miles divided by gallons. One clear check: 250 miles and 10 gallons give 25 mpg, which is also 4.00 gallons per 100 miles (about 9.41 L/100 km). A longer highway stretch often lands near 30–35 mpg in a compact SUV; a full-size pickup in city traffic may sit closer to 17 mpg.
In estimate mode the calculator computes fuel from known economy and distance. A 260-mile trip at 32 mpg needs about 8.13 gallons. Optional pump price shows the stretch cost. Annual distance with a price feeds the city / mixed / highway cost chart — an illustration of driving style, not a second set of city and highway sticker fields.
Multi-tank tracking: if you enter two consecutive fill-ups, the calculator computes a weighted average across the combined mileage — total miles divided by total gallons. For a mixed cycle it converts mpg to L/100 km first, weights by distance share, then converts back. At 40% city with 22 mpg city and 32 mpg highway that is about 27.1 mpg — not a window-sticker combined rating.
When you pick a fuel type, the calculator multiplies fuel volume by a tank CO₂ factor: gasoline 8.887 kg per gallon, diesel 10.180 kg per gallon, or E85 5.75 kg per gallon. With the US header the line is pounds and grams per mile. That is a combustion estimate, not type approval.
Measure fields are distance and fuel added. Estimate fields are distance and known consumption. Miles and gallons stay in US units: an entered distance is not silently converted to kilometers.
Trip cost in money is calculated on the trip fuel cost page. A year of service, insurance, and tires is calculated on annual running cost. This page reports tank economy or an assumed mpg. A window sticker is a lab cycle from FuelEconomy.gov, not this measurement.
One fill-up is closer to daily driving than a catalog figure, but it is still a snapshot. Cold starts, short hops, a roof rack, under-inflated tires, and heavy load all pull mpg down versus the sticker. Re-measure after a few tanks if you want a stable average.
Two odometer readings give distance as the difference: 43,460 minus 43,210 is 250 miles. Use that pair or the distance field, not both. If you enter a window-sticker combined mpg, the calculator shows how far the tank sits above or below that label. Fuel type on the US page is gasoline, diesel, or E85.
How to use
- Choose measure (distance and fuel added) or estimate (distance and known economy).
- In measure mode, enter miles and gallons from the pump, or use two odometer readings for distance.
- Click Calculate. The primary result is mpg; the secondary line shows gallons per 100 miles and L/100 km.
- Optionally enter fuel price and annual distance to see stretch cost and the driving-style chart.
- Compare with a window-sticker mpg if you want the percent gap versus the EPA label.
- Use the result in trip fuel cost. This page reports economy, not TCO.
mpg from the tank, not trip cost
Miles ÷ gallons gives tank mpg. Gallons per 100 miles is 100 ÷ mpg. That is fill-up economy, not TCO.
- mpg
- The measure-mode result with the US header. Higher is better. A compact hybrid may reach the mid-40s to about 50 mpg; many pickups sit near the high teens in city traffic.
- gal / 100 mi
- Consumption on a fixed distance: 100 ÷ mpg. At 25 mpg that is 4.00 gal / 100 mi. Useful when comparing thirst without the mpg illusion.
- Fuel
- Gallons added on that stretch. Pump price is an optional cost line, not a separate TCO.
Examples
Example 2 — compact SUV, mixed
- Mode: measure
- 360 miles
- 12 gallons
30 mpg
360 mi and 12 gal → 30 mpg (about 3.33 gal/100 mi). Typical mixed-road compact SUV band.
Example 3 — pickup, city traffic
- Mode: measure
- 204 miles
- 12 gallons
17 mpg
204 mi and 12 gal → 17 mpg (about 5.88 gal/100 mi). City thirst for a loaded full-size pickup.
Example 4 — estimate a trip
- Mode: estimate
- 260 miles
- 32 mpg
8.13 gal
260 ÷ 32 = 8.125 gallons for that distance. With a pump price the calculator also shows the stretch cost.
Example 5 — city / highway mix
- City 22 mpg
- Highway 32 mpg
- 40% of distance in the city
27.1 mpg
Distance-weighted: convert to L/100 km, mix 40/60, convert back. About 27.1 mpg. Not a window-sticker combined rating.
Example 6 — odometer pair
- Odometer 43,210 mi
- Odometer 43,460 mi
- 10 gallons
25 mpg
43,460 − 43,210 = 250 miles. 250 ÷ 10 = 25 mpg. Distance from the odometer pair at the pump.
Example 7 — hybrid vs sticker
- 400 miles
- 8 gallons
- Sticker 52 mpg
50 mpg · 3.8% below sticker
400 ÷ 8 = 50 mpg. Versus a 52 mpg sticker: (52 − 50) / 52 ≈ 3.8%. Compact hybrids often land in the mid-40s to about 50 mpg in mixed driving.
Common questions
How do I calculate fuel consumption from distance and fuel?
In US measure mode divide miles by gallons for mpg, or use 100÷mpg for gal/100 mi. 250 mi and 10 gal → 25 mpg (4.00 gal/100 mi). Metric mode uses litres÷km×100 for L/100 km.
What mpg do 250 miles and 10 gallons give?
25 mpg. That is tank economy: miles ÷ gallons. Consumption shown as gal/100 mi is 100÷25 = 4.00.
Does tank mpg replace a window sticker or EPA label?
No. The calculator reports your fill-up average. A window sticker is a lab or cycle rating — this page does not replace it.
Is this a trip fuel-cost or TCO calculator?
No. Here you get consumption (mpg or L/100 km). Trip fuel cost and car TCO live on separate motoring cards.
Is this a free fuel consumption calculator?
Yes. Enter distance and fuel (or estimate mode) and you see mpg or L/100 km at once. No account required.
How do I calculate mpg from a fill-up?
Divide the miles you drove by the gallons you added. For example, 250 miles and 10 gallons give 25 mpg, which is also 4.00 gallons per 100 miles.
How is measure different from estimate?
In measure mode the calculator divides miles by gallons added. With the metric header it divides liters by kilometers, times 100. In estimate mode it computes fuel as distance divided by mpg, or as distance times L/100 km divided by 100.
What is gallons per 100 miles?
Gallons per 100 miles is 100 divided by mpg. At 25 mpg that is 4.00 gal / 100 mi. The EPA uses this figure so that drivers can compare fuel use without the miles-per-gallon illusion.
Does tank mpg replace a window sticker?
No. The window sticker is a lab cycle from FuelEconomy.gov and the EPA. This calculator reports a tank stretch from your miles and gallons, which is useful for comparison but is not a certificate.
Why is my mpg below the sticker?
City traffic, short cold-start trips, a roof box, low tire pressure, heavy load, and aggressive acceleration all raise fuel use. A pickup in city traffic near 17 mpg or a compact SUV near 30 mpg mixed are common real-world bands.
How is the city and highway mix computed?
The calculator converts each mpg figure to L/100 km, weights by the city share of distance, then converts back. At 40% city with 22 mpg city and 32 mpg highway the mix is about 27.1 mpg. That is not a window-sticker combined rating.
How much fuel for 260 miles at 32 mpg?
260 ÷ 32 = 8.125 gallons. At 3.45 per gallon that is about 28.03 if you enter a price.
Do two odometer readings replace mileage?
Yes. Enter the reading at the previous fill and at the current fill; the calculator uses the difference as distance. For example, 43,460 minus 43,210 is 250 miles. Use either the odometer pair or the distance field, not both.
Is mpg using a US gallon or an imperial gallon?
With the US header the calculator divides miles by US gallons (about 3.785 L). An imperial gallon is larger (about 4.546 L), so the same miles and pump volume would yield a different mpg. This page does not convert UK gallons.
Where do I calculate trip fuel cost?
On the trip fuel cost page. A year of upkeep is on annual running cost. This page reports mpg, gallons per 100 miles, or L/100 km.
Knowledge sources
Use and cost come from your own numbers. Below is the FuelEconomy.gov and EPA vocabulary.
Page updated October 7, 2026.