Free propane calculator · grill tanks to 1,000-gallon tanks
How long will my propane last?
Pick your tank, read the gauge, and tell us what burns the gas. You get the hours of burn time, the day your tank runs dry, and when to call for a refill before it does.
Your tank, day by day
How the calculator works
Propane holds a fixed amount of energy: about 91,500 BTU per gallon (25.3 MJ per litre). Every appliance has a BTU-per-hour rating. Divide the energy in your tank by how fast your appliances use it and you get the burn time.
Example: a full 20 lb grill tank holds 4.7 gallons, which is 430,000 BTU. A 36,000 BTU three-burner grill on high burns through that in 12 hours. On medium (about 60% of the rating) it lasts close to 20 hours.
Home heating mode
For a house, the calculator estimates heat loss from your floor area, insulation level and the gap between your thermostat and the outdoor temperature, measured in heating degree days. It then divides by your furnace efficiency. Water heaters and other appliances are added as a daily amount: a propane water heater uses roughly 0.7 gallons a day for a typical household.
Real use varies with wind, sunshine, ceiling height and habits. Check your result against two gauge readings a week apart and adjust the insulation setting until they match.
How long does a propane tank last?
Burn time for a full tank at a steady rate. Large tanks are filled to 80% of their size, so a 500-gallon tank holds about 400 gallons.
| Tank | Propane | 10,000 BTU/h | 20,000 BTU/h | 40,000 BTU/h | 100,000 BTU/h |
|---|---|---|---|---|---|
| 1 lb canister | 0.24 gal | 2.2 h | 1.1 h | 0.5 h | 0.2 h |
| 20 lb tank | 4.7 gal | 43 h | 21.5 h | 10.8 h | 4.3 h |
| 30 lb tank | 7.1 gal | 65 h | 32.5 h | 16.2 h | 6.5 h |
| 40 lb tank | 9.4 gal | 86 h | 43 h | 21.5 h | 8.6 h |
| 100 lb tank | 23.6 gal | 216 h | 108 h | 54 h | 21.6 h |
| 120 gal tank | 96 gal | 36 days | 18 days | 9 days | 3.7 days |
| 250 gal tank | 200 gal | 76 days | 38 days | 19 days | 7.6 days |
| 500 gal tank | 400 gal | 153 days | 76 days | 38 days | 15 days |
| 1,000 gal tank | 800 gal | 305 days | 153 days | 76 days | 31 days |
Days assume the burner runs non-stop. A furnace cycles on and off, so a real tank lasts longer than this table shows.
Typical appliance ratings
| Appliance | BTU per hour | 20 lb tank on high |
|---|---|---|
| Portable heater (indoor-rated) | 4,000–18,000 | 24–108 h |
| Two-burner camp stove | 20,000 | 21.5 h |
| RV furnace | 20,000–35,000 | 12–21 h |
| Three-burner gas grill | 30,000–40,000 | 11–14 h |
| Patio heater | 40,000–48,000 | 9–11 h |
| Fire pit or fire table | 30,000–65,000 | 6.6–14 h |
| Turkey fryer | 50,000–60,000 | 7–8.6 h |
| Home furnace | 60,000–120,000 | n/a (bulk tank) |
How long will a propane tank last in winter?
For a 2,000 sq ft home with average insulation, a 90% furnace and a propane water heater, daily use depends mostly on the weather:
| Average outdoor temp | Gallons per day | 100 gal lasts | 200 gal lasts | 400 gal lasts |
|---|---|---|---|---|
| 50°F (10°C) | 2.9 | 34 days | 68 days | 136 days |
| 35°F (2°C) | 5.1 | 20 days | 39 days | 79 days |
| 20°F (−7°C) | 7.2 | 14 days | 28 days | 55 days |
So a full 500-gallon tank (400 gallons) heats an average home for roughly two to four months of winter. In a cold January in the northern states, plan on a delivery every six to eight weeks.
Reading your tank gauge
The dial under the lid of a large tank shows the percentage of the tank’s total size, not of a “full” fill. Tanks are filled to about 80% to leave room for the liquid to expand. Multiply the reading by the tank size to get gallons: 40% on a 500-gallon tank is 200 gallons. Smaller 20 lb tanks have no gauge. Weigh them: an empty one weighs about 17 lb (the “TW” stamp on the collar), so every pound above that is propane.
Gear that helps you never run out
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Propane questions
How long does a 20 lb propane tank last on a grill?
A full 20 lb tank holds 4.7 gallons (about 430,000 BTU). A typical 36,000 BTU three-burner grill on high uses it up in about 12 hours, and on medium in about 20 hours. Most people get 8 to 15 cookouts from one tank.
How long will a 500-gallon propane tank last?
A 500-gallon tank holds about 400 gallons when full. If propane only heats water and cooks, that can last most of a year. For whole-home heating in winter, an average 2,000 sq ft home uses 3 to 7 gallons a day, so a full tank lasts roughly 55 to 135 days depending on the weather.
How many gallons are in a 20 lb propane tank?
About 4.7 gallons. Propane weighs 4.24 lb per gallon, and a 20 lb tank is filled with 20 lb of propane. A 30 lb tank holds 7.1 gallons, a 40 lb tank 9.4 gallons and a 100 lb tank 23.6 gallons.
Why is my 500-gallon tank only filled to 80%?
Liquid propane expands when it warms up. Filling to about 80% leaves space for that expansion, so the safety valve does not open on a hot day. A gauge reading of 80% means your tank is full.
When should I order more propane?
Order when your gauge reads 20 to 30%. In cold weather suppliers get busy, and running a tank empty can mean a mandatory leak test before they refill it. The calculator shows the date your tank reaches your reorder level.
How much propane does a house use per month in winter?
A typical 2,000 sq ft home heated with propane uses around 100 to 200 gallons per month in the coldest months, depending on climate, insulation and thermostat setting. Mild months can drop to 30 to 60 gallons.
How do I tell how much propane is left in a small tank?
Weigh it. The tare weight (TW) stamped on the collar is the empty weight, usually about 17 lb for a 20 lb tank. Subtract it from the current weight to get the pounds of propane left, then divide by 4.24 for gallons. Pouring warm water down the side and feeling for the cold line also works.