Why is my propane tank only 80 percent full?

80 percent

Have you ever noticed that your propane tank is never 100 percent full?

There’s a (propane safety) reason for that: You see, propane expands in the presence of heat (just like water).

That’s why propane tanks, which are exposed to heat in the summer, are filled to only about 80 percent of their capacity – leaving space for propane to expand as summer heats up (it’s also why you should not paint your outdoor propane tank a dark color, which absorbs heat).

To calculate the working capacity of your propane tank, simply multiply the tank’s total capacity by 0.8. For example,

Tank size (gallons) 80 percent (gallons)
120 96
150 120
200 160
250 200
500 400

When we deliver propane to your home, our drivers follow the 80 percent rule.

For safe, reliable propane deliveries in Southwest Iowa, trust Pelgas. Let our trained technicians take care of your propane tank this summer, along with propane system maintenance, regulator change-outs, and more!