Fuel log & MPG tracker
Log each fill-up and see your MPG tank by tank, your running average and what driving really costs you per mile. It's saved in your browser. No app, no account.
How the tracker computes MPG
Each full fill-up closes a measurement: miles since the previous full fill-up ÷ all the gallons added since then. Partial fills are carried forward, which keeps the math honest when you only put in $20. Your average is total miles ÷ total gallons across measured tanks, not an average of averages, so one short tank can't skew it.
Cost per mile is the fuel you paid for after the first fill-up divided by the miles driven since then. The first fill-up only sets the starting line. For one-off readings use the MPG calculator. To budget a month of commuting, try the commute cost calculator.
Questions drivers ask
Where is my fuel log stored?
Only in this browser, using localStorage. Nothing is uploaded and there is no account. Export a CSV to back it up or move it to another device, and use "Clear log" to delete it.
Why does the first fill-up show no MPG?
MPG is measured between two full fill-ups. The first entry sets the starting odometer; every later full fill-up gives a reading for the miles since the previous one.
What happens if I don't fill the tank completely?
Tick "partial fill". The tracker carries that fuel and distance forward and computes MPG at the next full fill-up, so your average stays accurate.
How many fill-ups do I need for a reliable average?
Three to five full tanks give a solid average. Single tanks swing with weather, traffic and how exactly the pump clicked off.