Gas mileage calculator – your real mpg

How to calculate your gas mileage

1. Fill up to full

   Fill the tank completely and note the odometer reading.

2. Log every fill-up

   Enter the date, odometer, gallons and the amount paid. Tick “Filled up to full” for full tanks.

3. Read your mpg

   From the second full tank on, your real average mpg and costs appear at the top.

How to improve your gas mileage

• Keep tyres at the pressure on the door sticker. Low pressure costs fuel.
• Ease off on the highway. Fuel use climbs steeply at higher speeds.
• Remove roof boxes and racks when you do not need them.
• Combine short trips: a cold engine uses the most fuel.

Log your fill-ups for a few weeks before and after a change, and the diary shows whether it made a difference.

The formula behind it

Fuel cost = distance ÷ miles per gallon × price per gallon. In metric: distance × litres per 100 km ÷ 100 × price per litre. Example: 300 miles at 30 mpg is 10 gallons; at $3.50 a gallon that is $35, or $17.50 each for two people.

Fuel Studio converts between US mpg, UK mpg, km/l and l/100 km for you, so you can mix a European car spec with a US trip, or the other way round.

Track your real mileage

Window stickers and brochures are measured on test cycles; everyday driving often uses more. Log each fill-up with the odometer reading and tick “Filled up to full” when the tank is full. From the second full tank on, Fuel Studio shows your real average, the cost per 100 miles and your spending per month. The diary stays in this browser; export it as CSV any time.

Electric or gas: compare the energy cost

Enter how far you drive in a year, the electric car’s consumption in kWh, your home electricity rate and the public charging price, and how much you charge at home. Fuel Studio shows the energy cost per 100 miles and per year for both cars. Purchase price, insurance and maintenance are not part of this comparison.

How to split gas money for a road trip or carpool

For a shared ride, enter everyone in the car in “People sharing” – the driver included. Fuel Studio divides the fuel plus tolls and parking evenly. For a round trip, tick “Round trip” so the drive home is counted too.

Fair carpools often agree on something simple: the passengers pay the fuel, the driver covers wear and tear. If someone joins only for part of the way, work out their part separately with that distance and add it to their share. Settle up with the total on screen rather than a guess: it avoids the classic “roughly twenty each” that never quite matches the receipt.

MPG to l/100 km and back

US cars are rated in miles per US gallon, British cars in miles per imperial gallon, and most other countries use litres per 100 km – where lower means more efficient. Pick the unit next to “Fuel economy” and Fuel Studio converts for you.

This matters when you rent a car abroad: a European spec sheet with 6.5 l/100 km is about 36 US mpg.

Spend less on gas without driving less

• Compare before you fill up. In Germany, France, Spain and Austria the “Prices” tab shows every nearby station; the box “Saved on a 50 l tank” tells you what the cheapest one saves against the average.
• Watch your own trend. Save the stations you pass with the star – “My stations” shows whether their price went up or down since you last looked.
• Drive steadily. Higher highway speeds and roof boxes raise consumption noticeably; your fill-up diary shows the effect in real numbers.
• Check tyre pressure. Under-inflated tyres cost fuel and grip.