What size propane tank do I need?
Match the tank to what you burn. One or two appliances fit a 120 or 250 gallon tank. A house with a propane furnace usually has a 500. A bigger tank burns the same fuel and brings fewer, larger deliveries. The table below counts deliveries a year for four typical uses, so you can see what each size means in practice.
The four home sizes
Tank size is water capacity. A tank is filled to 80% to leave room for the gas to expand, so a 500 holds 400 gal of propane. The size column shows two sources. They are within a few inches of each other on the larger tanks. On the 120, Ferrellgas lists an upright tank (54.5 in tall) and Propane101 a horizontal one (68 in long). Propane101 calls its numbers approximate. Measure yours before you plan a pad or a trench. Measure yours before you plan a pad or a trench.
| Tank | Holds at 80% | Ferrellgas size | Propane101 size |
|---|---|---|---|
| 120 gal | 96 gal | 54.5 in tall, 30 in diameter | 68 in long, 24 in diameter |
| 250 gal | 200 gal | 7 ft 10 in long, 30 in diameter | 92 in long, 30 in diameter |
| 500 gal | 400 gal | 9 ft 11 in long, 37.5 in diameter | 120 in long, 37 in diameter |
| 1,000 gal | 800 gal | 16 ft 1.5 in long, 41 in diameter | 190 in long, 41 in diameter |
Sources: Ferrellgas, propane tank sizes and Propane101, tank sizes.
What suppliers say each one suits
- 120 gal: only running 1-2 appliances on propane (Ferrellgas).
- 250 gal: sufficient for a heating system for modest-sized homes (Ferrellgas).
- 500 gal: the standard size for most households (Ferrellgas).
- 1,000 gal: generally reserved for large industrial and commercial projects (Ferrellgas).
That is one supplier's view, and it fits the numbers below.
Deliveries a year by use and size
The yearly gallons come from EIA's 2020 household survey, the same averages as on propane use per month. The table assumes you call when the gauge reaches 20% and the driver fills to 80%, so a delivery brings 60% of the tank: 72 gal into a 120, 150 into a 250, 300 into a 500 and 600 into a 1,000. Divide a year's gallons by that and you get the deliveries. This is my arithmetic on averages, not what your house does.
| Use | Gallons a year | 120 gal | 250 gal | 500 gal | 1,000 gal |
|---|---|---|---|---|---|
| Hot water only | 183 | 2.5 | 1.2 | 0.6 | 0.3 |
| Heat only, U.S. average | 390 | 5.4 | 2.6 | 1.3 | 0.7 |
| Heat and hot water, U.S. average | 573 | 8.0 | 3.8 | 1.9 | 1.0 |
| Heat and hot water, Illinois average | 936 | 13.0 | 6.2 | 3.1 | 1.6 |
Read it like this: a house that heats with propane and has a propane water heater burns about 573 gal in an average U.S. year. A 250 would need 3.8 deliveries, a 500 would need 1.9. In the Illinois row the 250 is down to a delivery every 1.9 months on average, with most of them in winter.
Picking between two sizes
- Plan for the winter months. A furnace burns most of its gallons from November to March, so a tank that is fine on a yearly average can still run low in January.
- Check your delivery slips for the real yearly total, then use the table row that is closest.
- Ask your supplier whether they own or rent the tank and what a larger one costs. I have no prices for that, and they vary by supplier.
- For a generator on top of the house load, size up and read the furnace page for the heating part.
Next step
If you already have a tank, enter two dated gauge readings in the calculator to get your own gallons per day. The propane tank percentage chart turns a gauge percent into gallons for all sizes, and cost to fill a tank prices a delivery.