How do I account for partial fuel-ups?

If you can't completely fill up to the top when you're at the pump and you want to track the fuel-up in Fuelly, check the box next to This is a partial fuel-up. This will let Fuelly know that you have a partial tank. Once marked, Fuelly won't calculate MPG for that fuel-up until your next full fillup. However, your partial fills will contribute to your overall average MPG. Fuelly's calculations rely heavily on you filling your tank to the top because it uses the difference from full to calculate fuel economy on individual fuel-ups.