Volume meter for gas cans?
 

I get my gas using my supermarket's discount program, so I buy the maximum 30 gallons every time by filling my tank and red 5-gallon gas cans.

I can easily calculate what goes INTO the cans by subtracting my car's fill-up volume from the 30-gallon total. But I put some of the gas from the cans into my wife's car between my fillups. This leaves me with estimates of the cans' actual contents. Anyone know how I can accurately gauge what I pour into my car when I'm not at the filling station, but rather in my garage?

If I have to, I can do the math at the pump and track the contents of each can as I fill them, then track which car they go into. The much lazier way is what I asked about above. Is there a home meter for this kind of situation?

You could do the filling in one can increments so you're always only putting in 5 gallons.

I thought of that too, but the cans aren't PRECISELY 5 gallons. This is probably the best way, though. At the pump I have to make sure I record what goes into my car, then fill up 3 5-gal cans with precisely 5 gallons each, then 30 - 15 - my fill up = the leftover in the 4th can.

get a scan gauge and once it's calibrated you are done.

I would put increment marks on the can with permanent marker, up to 5 gallons. Do this by starting with an empty can on a level surface and putting marks on as you reach every increment with the gas pump. It will make it easier to track how much you put into the car, just check the level when you set the can back down. Maybe even tie a scratch pad to the handle of the can.

Subscribed: I'm going to have to deal with this myself soon,

I'm thinking fill can with 1 gallon (trusting the pump accuracy) mark with permanent marker; repeat for 2- 5 gallons (maybe even 5.5 gallons)

My gas cans were $8.50 apiece at Wal-Mart, and they have markers at each gallon as well as at the 5-gallon capacity level. They're not precise, I'm sure, but they're a good enough gauge.

Mine are not even close (old cans) I put ~6.5 gallons if I fill to the 5 gallon line.

BUT if anyone needs a cheap gas can; Sams club has 6 gallon rated cans for 4.8x each. May just be to hurricane prone areas though, because it was in the hurricane preparedness area. . . . .

I think I've got the Rube Goldberg solution here!

1. Measure the specific gravity of your gas. It may vary about +-5% according to wikipedia.
2. Weigh your gas can.
3. Fill vehicle.
4. Weigh gas can again.
5. Subtract line 4 from line 2.
6. Divide line 5 by line 1.

Staples has a $130 pediatric scale with 44lb capacity and 10 g resolution. 20 gram accuracy would mean an error of at most 29 mL or .0077 gallons.

Wasn't this problem a puzzle on a die hard movie?

The simplest way I say is just measure how much you put in the can according to the pump, it might not be 5 gallons exactly, but it should be close.

I also second the scangauge. Mines 99% accurate after only one fill up.