Average price per gallon

[NBtarheel33]

Shouldn't the average price per gallon be given by (All-time amount spent) divided by (All-time gallons consumed)? This is how I calculate average PPG in my spreadsheet, but it is off by a penny from Fuelly. What's up?

[pb]

Which stat are you talking about? On vehicle profile pages or on your dashboard?

If vehicle profile pages, do you have your Cost Analysis Period set to "All Time"? If you're talking about the dashboard, keep in mind we use a Running Average there.

[NBtarheel33]

This would be on the vehicle profile pages themselves.

[NBtarheel33]

And yes, I do have the profile pages set to "All-time".

[pb]

And it's off by .01 compared with your calculations? Could it be a rounding issue? Are you rounding to two decimal places in your spreadsheet?

[NBtarheel33]

Look at Little Bertha's page (the Saturn SL2). All-time gallons consumed is 3208.23, and all-time total spent is $8,530.78. So shouldn't the all-time average price per gallon be given by $8,530.78/3208.23 = $2.6590 = $2.66 to the nearest penny? And if so, why is the all-time average price per gallon under "Cost Analysis" showing $2.67?

[pb]

oh ok, just took a look and we're doing a straight average of all the prices you have entered. We're not doing anything with the total distance driven.

So the average of all 339 prices you have entered so far is 2.672920, and because you enter the price/gallon that's your average price per gallon.

[NBtarheel33]

IOW, a straight average price per gallon rather than a weighted average price per gallon. Gotcha. Interesting that the two are so close together, though I suppose that might be different if I had more partial fuel-ups.