Propane Tank Size Chart
By windflash · Published Oct 18, 2026 · Updated Oct 18, 2026
Propane tank sizes: gallons, pounds and cost to fill
Large tanks are filled to 80% of water capacity. Pounds use 4.24 lb per gallon. Cylinders are listed by nominal propane weight. Values are approximate; check your tank's data plate, since dimensions and capacities vary by manufacturer.
| 20 lb cylinder | 4.7 gal | 4.7 gal | 20 lb | Gas grills | $12.44 |
| 30 lb cylinder | 7.1 gal | 7.1 gal | 30 lb | RVs and camping | $18.67 |
| 40 lb cylinder | 9.4 gal | 9.4 gal | 40 lb | RVs and small heaters | $24.89 |
| 100 lb cylinder | 23.6 gal | 23.6 gal | 100 lb | Water heaters and cabins | $62.22 |
| 100 gal | 100 gal | 80 gal | 339 lb | Small appliance loads | $211.04 |
| 120 gal | 120 gal | 96 gal | 407 lb | Water heater, range, fireplace | $253.25 |
| 250 gal | 250 gal | 200 gal | 848 lb | Small whole-house heating | $527.60 |
| 500 gal | 500 gal | 400 gal | 1,696 lb | Whole-house heating (most common) | $1,055.20 |
| 1000 gal | 1,000 gal | 800 gal | 3,392 lb | Large homes, multiple appliances | $2,110.40 |
Cost is fuel only at the EIA U.S. average price for the week of Oct 12, 2026. Delivery fees, minimum deliveries and tank rental are extra.
Which propane tank size do I need?
- Grill: a 20 lb cylinder.
- Water heater, range or fireplace: often a 100 lb cylinder or a 120-gallon tank.
- Whole-house heating: usually a 250 to 1,000-gallon tank. Our estimate for a 2,000 sq ft home with average insulation is about 690 gallons in Connecticut and 980 in Minnesota in a winter. Run your numbers in the heating cost calculator.
Horizontal, vertical and underground tanks
Large tanks come as above-ground horizontal tanks, vertical tanks and buried (underground) tanks. The capacity in gallons is what sets how much fuel you can store; the shape and placement affect the footprint and the installation. Your propane dealer and local codes decide what is allowed on your property.
How many pounds of propane in a 100 gallon tank?
About 339 pounds at the standard 80% fill (80 gallons × 4.24 lb). See the full answer and math.
Gallons to pounds converter
Frequently asked questions
What size propane tank do I need for a house?
For whole-house heating, our estimate for a 2,000 sq ft home with average insulation is about 690 gallons in Connecticut and 980 in Minnesota over a winter. A 500-gallon tank holds about 400 gallons at 80% fill; check the calculator for your own numbers.
Why are propane tanks only filled to 80%?
Liquid propane expands as it warms, so tanks are filled to about 80% to leave room for expansion. That is why a 500-gallon tank holds about 400 gallons of propane.
How many pounds of propane are in a 500-gallon tank?
At 80% fill, 400 gallons × 4.24 lb per gallon is about 1,696 pounds.
How much does it cost to fill a propane tank?
At the U.S. average of $2.64 per gallon, a 500-gallon tank at 80% costs about $1,055.20 in fuel. Delivery fees, minimums and tank rental are extra.
Current prices by state: propane prices per gallon.