Free iPhone app · no account
Gas Mileage Tracker: the MPG your car actually gets
Not the number on the window sticker. Your car gets whatever your commute, your right foot and your last set of tyres say it gets. Log a fill-up in ten seconds and the app works out the real figure, tank by tank, along with what fuel costs you per mile and per month.
Android version in the works. The calculators here work on anything with a browser.
2019 Honda Civic · last tank
31.2
miles per gallon
Average
29.4
Per mile
$0.11
This month
$142
Fill-ups
64
Example data. The app calculates all of this from the odometer and the gallons.
Free calculators
No sign-up, no ads in the way. They run in your browser and nothing you type leaves the page.
Gas mileage calculator
Two odometer readings and the gallons you put in. Works in MPG, L/100 km and km/L.
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Fuel cost calculator
What a trip costs in fuel, and what each passenger owes you when you split it.
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Cost per mile calculator
Fuel plus insurance, tyres and depreciation. The number you quote or deduct.
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Three taps at the pump
The whole point is that it has to be faster than the receipt going in your pocket, or you stop doing it by week three.
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01
Type the odometer
The app shows your last reading right under the field, so you can tell instantly if you fat-fingered a digit.
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02
Gallons and price
Straight off the pump display. Total cost fills itself in. Station and notes are optional and most people skip them.
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03
That is it
From the second fill-up on you get MPG for that tank, a running average, cost per mile and a monthly total you did not have to add up.
Why bother logging it
The dashboard readout lies, politely. Trip computers estimate fuel flow rather than measuring the tank, and they lean optimistic. Tank-to-tank arithmetic uses fuel you actually paid for.
A drop in MPG is a symptom. Under-inflated tyres, a dragging brake, a failing sensor and a clogged filter all show up as a few lost miles per gallon weeks before they show up as a warning light.
Fuel is the second biggest line in owning a car. Most people can name their insurance premium to the dollar and have no idea what they spend on petrol. One number per month fixes that.
Mileage claims need records, not memory. If you deduct vehicle costs or bill a client for travel, a dated log beats an estimate. Pro exports the lot to CSV.
What is in the app
- ✓ MPG per tank and a running average, using the full-tank method
- ✓ Cost per mile, total spent, and a this-month figure
- ✓ Charts: MPG trend, monthly spending, price per gallon over time
- ✓ Several vehicles, each with its own history
- ✓ Partial fill-ups handled properly instead of silently wrecking the average
- ✓ Full fill-up history you can edit when you mistype something
- ✓ CSV export for taxes or a spreadsheet (Pro)
- ✓ Dark mode, and no account anywhere
Free. Pro is a one-time purchase, not a subscription.
What a gas mileage tracker does
A gas mileage tracker is a fuel log. You record the odometer and the fuel at every fill-up, and it does the tank-to-tank arithmetic that turns those entries into miles per gallon, cost per mile and a monthly fuel total.
People used to keep this in the glovebox on a folded receipt, then in a spreadsheet. The reason to use an app instead is not the maths, which is one division. It is that the log has to survive contact with a rainy forecourt. If entering a fill-up takes longer than putting the receipt in your pocket, you stop after three weeks, and an abandoned log is worth exactly nothing.
So the whole design of this one points at one number: seconds to log a fill-up. The last odometer reading sits under the field so a typo is obvious. Total cost fills itself in. Station and notes are there and you can ignore them forever.
Tracker, or just the calculator?
Both are on this site. They answer different questions.
One tank, once
Use the gas mileage calculator. Nothing to install, nothing to remember.
Every tank, from now on
Use the app. One tank tells you almost nothing, because weather, traffic and how you drove move it 10 percent on their own. A run of tanks is the only thing that shows a real change.
Worth reading
How to calculate gas mileage
The formula, the two-fill-up method, and the mistakes that make the number wrong.
What is good gas mileage?
What counts as good in 2026 by body style, and where your car sits.
How to improve gas mileage
What actually moves the number, ranked, and the tricks that do nothing.
Fuelly alternative
Fuelly is a website with a thin app. Here is the honest comparison.