How long does a propane tank last?

Figures checked Nov. 10, 2026

It depends on the tank and what it runs. Divide the heat in the tank by your appliance's input rating: hours = gallons × 91,300 Btu ÷ the appliance's Btu per hour. Type your tank and the rating from your appliance's rating plate into the calculator below, and we do the sums.

What you need	Where to find it
Propane in the tank	the gauge on a big tank; the net weight label, or the scale minus the TW stamp, on a cylinder
Appliance input, Btu per hour	the appliance's rating plate
Hours a day it runs	your own estimate

How long your propane will last

The sums behind this tool are checked against 4 run times printed by a heater maker (ours must come out at or below them), and 31 checks in all, including the limits where it gives no number.

How the calculator works

First it works out the gallons in your tank. Big tanks are filled to about 80% of their size, and the gauge shows a share of the whole tank. Cylinders are filled by weight, and a gallon of propane weighs about 4.24 pounds.

Then it multiplies the gallons by the heat in a gallon and divides by your appliance's input. For run times we use 91,300 Btu per gallon, the lowest official figure we hold, so the answer errs on the short side.

It also works at the full input rating the whole time, and rounds hours and days down. Above a year, it gives no number and asks you to check with your propane supplier.

Appliance ratings: examples only

The best figure is always the one on your appliance's rating plate. Gas code tables say the gas an appliance uses should be found from the maker's input rating, and give the figures below only as examples. Check your appliance's rating plate before you rely on any of them.

Appliance (example)	Input, Btu per hour
Warm air furnace, single family	100,000
Hydronic boiler, single family	100,000
Storage water heater, thirty to forty gallon	35,000
Storage water heater, fifty gallon	50,000
Range, freestanding	65,000
Clothes dryer	35,000
Gas fireplace, direct vent	40,000
Gas log	80,000
Barbecue	40,000

How long does a propane tank last for a whole house?

The calculator takes one appliance's rating at a time, so work out each appliance separately. For example, say a furnace rated at 100,000 Btu per hour runs 8 hours a day: type both into the calculator with your tank size. The answer is how long the tank would last if the furnace were the only appliance using it.

The calculator counts every hour you type in at the full rating, so the hours figure matters most. For the whole house, or if you're unsure of the hours, ask your propane supplier about your past deliveries.

How long does a 20-lb propane tank last?

A full 20-lb cylinder holds about 4.7 gallons by suppliers' figures, but many exchange cylinders hold about 15 pounds of propane instead. The calculator asks whether yours was refilled or exchanged, and uses the lower fill if you're not sure.

For a grill, use the burner rating on its label. The 20-lb tank page has more on exchange fills.

How long does a 500-gallon or 100-lb tank last?

The same sum, with a bigger tank. A 500-gallon tank holds about 400 gallons when full, and a 100-lb cylinder about 23 gallons. Choose your size in the calculator, or see the propane tank sizes chart.

Before it runs out

The calculator counts down to empty. Don't let a tank run empty: ask your propane supplier when to reorder.

Patio heaters, grills and camp stoves are outdoor-only. Indoor heaters on a cylinder need fresh air and a working CO alarm in the room, and shouldn't be left running unattended or while you sleep. Have propane appliances installed and serviced by a certified propane technician.

Questions people ask

How long does a propane tank last on a grill?

Divide the heat in the tank by the grill's Btu rating from its label. The calculator does it for you and errs on the short side.

How long does propane last in a tank?

In use, it depends on your appliances and hours. For how long a cylinder can go on being refilled, see does propane go bad?

Why is your run time shorter than the label on my heater?

We use the lowest official heat figure for propane, the full input rating, and round down. Follow your appliance's own label and instructions.

How long does a 500-gallon propane tank last in winter?

It depends on your furnace and other appliances. The calculator works out one appliance at a time from its rating plate; for the whole house, ask your propane supplier about your past deliveries.

Before you light it

Carbon monoxide (CO) can kill. US Consumer Product Safety Commission (Official): “Fuel-burning heating systems, including furnaces and fireplaces, can produce CO, an odorless, colorless and deadly gas.” Source(opens in a new tab)
Fit CO alarms and test them. US Consumer Product Safety Commission (Official): “CO alarms should be placed on every level of the home and outside sleeping areas.” “Test the alarms every month to make sure they are working.” Source(opens in a new tab)
Have appliances checked every year. US Centers for Disease Control and Prevention (Official): “Have your heating system, water heater and any other gas, oil, or coal burning appliances serviced by a qualified technician every year.” Source(opens in a new tab)
Chimneys and vents too. US Fire Administration (Official): “Have chimneys and vents cleaned and inspected at least once a year.” Source(opens in a new tab)
If a CO alarm sounds (US: call 911): US Centers for Disease Control and Prevention (Official): “If the detector sounds leave your home immediately and call 911.” Source(opens in a new tab)
Know the signs. US Centers for Disease Control and Prevention (Official): “The most common symptoms of CO poisoning are headache, dizziness, weakness, nausea, vomiting, chest pain, and confusion.” Source(opens in a new tab)
Carbon monoxide (CO). CPSC (Official): "Fuel-burning heating systems, including furnaces and fireplaces, can produce CO, an odorless, colorless and deadly gas." "CO alarms should be placed on every level of the home and outside sleeping areas." Source(opens in a new tab)
If you smell gas (US: call 911). Connecticut Public Utilities Regulatory Authority (Official): "If the smell is strong or you are unsure, leave the building and then call." "Go to a phone that is not near the smell and call your propane company right away." "Don't smoke or strike any matches." "Don't flip light switches on or off." "Put out all open flames." "Call your propane company or 911 for help." This is general advice from one state's regulator: follow your own propane supplier's emergency instructions too. Source(opens in a new tab)
Keep propane cylinders outdoors. Utah State Fire Marshal (Official): "Never store a cylinder inside a house, building, or a garage." Source(opens in a new tab)
Outdoor-only heaters, grills and stoves stay outdoors. Mississippi State University Extension (Official), on outdoor-use-only heaters: "Never use them inside, even temporarily." Source(opens in a new tab)
Don't leave a heater running unattended or while you sleep. Mississippi State University Extension (Official): no fuel-burning appliance "should be left unattended or operated while sleeping." Source(opens in a new tab)
Have a working CO alarm in the room. Missouri Department of Natural Resources (Official): "Never operate a gas space heater in a room that does not have a working carbon monoxide alarm." Source(opens in a new tab)

Sources for this page

16 figures, each with its source

Every figure on this page, with its source. Open one to see the exact words on the source page and how it was checked.

Example appliance input: Barbecue (gas grill) (check your appliance's rating plate): 40,000 Btu per hour Official
From City of Pleasanton CA Building & Safety handout: Gas Pipe Sizing, Table 12-1 (2007 California Plumbing Code), which says: “Barbeque | 40,000” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Example appliance input: Clothes dryer, domestic (check your appliance's rating plate): 35,000 Btu per hour Official
From City of Pleasanton CA Building & Safety handout: Gas Pipe Sizing, Table 12-1 (2007 California Plumbing Code), which says: “Clothes dryer, Type 1, domestic | 35,000” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Example appliance input: Warm-air furnace, single family (check your appliance's rating plate): 100,000 Btu per hour Official
From City of Pleasanton CA Building & Safety handout: Gas Pipe Sizing, Table 12-1 (2007 California Plumbing Code), which says: “Warm air furnace, single family | 100,000” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Example appliance input: Gas fireplace, direct vent (check your appliance's rating plate): 40,000 Btu per hour Official
From City of Pleasanton CA Building & Safety handout: Gas Pipe Sizing, Table 12-1 (2007 California Plumbing Code), which says: “Gas fireplace, direct vent | 40,000” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Example appliance input: Gas log (check your appliance's rating plate): 80,000 Btu per hour Official
From City of Pleasanton CA Building & Safety handout: Gas Pipe Sizing, Table 12-1 (2007 California Plumbing Code), which says: “Gas log | 80,000” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Example appliance input: Hydronic boiler, single family (check your appliance's rating plate): 100,000 Btu per hour Official
From City of Pleasanton CA Building & Safety handout: Gas Pipe Sizing, Table 12-1 (2007 California Plumbing Code), which says: “Hydronic boiler, single family | 100,000” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Example appliance input: Range, freestanding, domestic (check your appliance's rating plate): 65,000 Btu per hour Official
From City of Pleasanton CA Building & Safety handout: Gas Pipe Sizing, Table 12-1 (2007 California Plumbing Code), which says: “Range, freestanding, domestic | 65,000” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Example appliance input: Water heater, storage, 30-40 gallon (check your appliance's rating plate): 35,000 Btu per hour Official
From City of Pleasanton CA Building & Safety handout: Gas Pipe Sizing, Table 12-1 (2007 California Plumbing Code), which says: “Water heater, automatic storage, 30 to 40 gallon | 35,000” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Example appliance input: Water heater, storage, 50 gallon (check your appliance's rating plate): 50,000 Btu per hour Official
From City of Pleasanton CA Building & Safety handout: Gas Pipe Sizing, Table 12-1 (2007 California Plumbing Code), which says: “Water heater, automatic storage, 50 gallon | 50,000” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Heat content of propane, for run times only (lowest official figure, kept as a safety margin): 91,300 Btu per gallon Official
From USDA Forest Service, Forest Products Laboratory: Fuel Value Calculator (updated July 2004), hosted by Nebraska Energy Office, which says: “Propane | gallon | 91,300 | 71,900 | 79%” Open the source (opens in a new tab)
Checked Nov. 10, 2026.
Gallons in a full 100 lb cylinder: 23 gallons Other source
From Ferrellgas (propane supplier): How to Choose the Right Propane Tank Size?, July 24 2025, which says: “100-lb: Holds 23 gallons of propane.” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Propane in a 20 lb exchange cylinder (net weight): 15 pounds of propane Other source
From Blue Rhino (exchange-cylinder maker): How much propane does Blue Rhino put in its tanks?, which says: “Blue Rhino propane grill tanks contain a net weight of 15 lbs. of propane.” Open the source (opens in a new tab)
Checked Nov. 9, 2026.
Gallons in a full 20 lb cylinder: 4.7 gallons Other source
From Ferrellgas (propane supplier): How to Choose the Right Propane Tank Size?, July 24 2025, which says: “20-lb: Holds up to 4.7 gallons of propane.” Open the source (opens in a new tab)
Checked Nov. 10, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026. A blind check looked it up again on Nov. 10, 2026 without seeing our figure: the two agreed.
Weight of a gallon of propane: 4.24 pounds per gallon Other source
From U-Haul (retailer): 20-lb Steel Propane Tank product page (answer in the page's customer Q&A, 2021), which says: “The Propane that should be going into this tank only would weigh about 4.24lbs per gallon of propane.” Open the source (opens in a new tab)
Checked Nov. 10, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026. A blind check looked it up again on Nov. 10, 2026 without seeing our figure: it didn't find a better source, so this figure stands.
Maximum fill of a propane tank: 80% Official
From Utah State Fire Marshal: LP-Gas Basic Filling Procedures, which says: “To allow for expansion, propane containers are to be filled only to 80% of their capacity.” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026. A blind check looked it up again on Nov. 10, 2026 without seeing our figure: the two agreed.
500-gallon propane tank: usable gallons at 80%: 400 gallons Other source
From Ferrellgas (propane supplier): How to Choose the Right Propane Tank Size?, July 24 2025, which says: “Holds 400 gallons of propane.” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026, and its source label was corrected afterwards.