I’m thinking about brewing in the morning and I knew my propane was getting low. So I just bought a brand new propane tank from Lowe’s so I could fully use the propane left in the Blue Rhino exchange tank before swapping it out. Also so I wasn’t stuck without a way to finish the boil if I did run out.

My local propane fill station charged $3.29 per gallon so I paid $15.88 for 4.5 gallons. So I weighed the tank and got 35.2 lbs on a body weight scale and subtracted the tear weight of 16.6 lbs. I came up with 18.6 lbs. Now my Blue Rhino exchange tank is labeled as 15 lbs of propane. I called a local exchange place and the price is $18.99. So a full tank from Blue Rhino should weigh 31.6 lbs right?

I also weighed my almost empty feeling Blue Rhino tank and it weighed 19.4 lbs and used 16.6 lbs as tear weight but I’m not sure if that was correct weight leaving me 2.8 lbs of propane. Is there a way to figure out how many gallons of propane is in 2.8 lbs? So I could then calculate if it is 1/4 left or 1/8 left? It looks like 4.7 gallons is full for 20 pound tank.