How Long Does a 20 lb Propane Tank Last on a Fire Table?

Updated September 19, 2026

A full 20-pound propane cylinder will run a typical 40,000–60,000 BTU fire table for roughly 7–11 hours at maximum output. A lower flame setting can extend the runtime, while wind, cold weather, the burner design and the actual amount of propane in the cylinder can shorten or lengthen it.

You do not need to rely on a generic estimate. If you know the fire table’s BTU-per-hour rating, a simple calculation will give you a useful starting point.

20 lb propane tank runtime chart

A full 20-pound cylinder contains about 430,000 BTU of fuel. Divide that figure by the appliance’s rated input in BTU per hour.

These are mathematical estimates, not promised operating times. They assume 20 pounds of usable propane and continuous operation at the stated maximum input.

How to calculate your fire table’s runtime

The U.S. Energy Information Administration lists propane at 91,452 BTU per gallon. A 20-pound cylinder holds roughly 4.7 gallons when filled to its rated propane capacity, which works out to approximately 430,000 BTU.

Estimated hours = 430,000 ÷ burner BTU per hour

For a 50,000 BTU fire table:

430,000 ÷ 50,000 = 8.6 hours

Use the appliance’s input rating from its rating plate or manual. Do not substitute a marketing description such as “high heat” or assume that two similarly sized tables use fuel at the same rate.

Why actual runtime differs from the calculation

The cylinder may not contain 20 pounds of propane

“20 lb” describes the cylinder’s rated propane capacity. A refill or exchange cylinder may contain less, and a partially used tank obviously starts with less energy. Weighing the cylinder gives a better estimate than judging by how heavy it feels.

Most people do not run the burner on high continuously

If the control valve reduces fuel flow, a lower flame generally extends runtime. Running at approximately half the maximum input could approach twice the calculated high-setting runtime, but the relationship is not guaranteed to be perfectly linear. Use the manufacturer’s data when it provides low- or medium-setting consumption.

Weather affects performance

Wind carries heat away and may lead users to raise the flame. Cold weather lowers cylinder pressure and can limit vaporization, especially as the fuel level drops. Never apply an external heat source to a propane cylinder.

Burner condition and installation matter

Blocked burner ports, damaged hoses, an incorrect regulator or an unauthorized conversion can cause poor operation and create a safety hazard. Follow the fire table’s manual and have repairs or fuel conversions performed by a qualified professional.

How long will a tank last at a lower flame?

If you know the approximate input at the lower setting, use that number in the same formula. For example, a 50,000 BTU burner operating at an actual 25,000 BTU per hour would have a theoretical runtime of about 17.2 hours.

If the manual lists only the maximum rating, track several normal sessions instead:

1. Start with a known fill weight.
2. Record how long the table operates and the settings you use.
3. Weigh the cylinder again after it has cooled and the valve is closed.
4. Use the measured fuel consumed to estimate future sessions.

This gives a planning number based on your fire table and habits instead of an internet average.

How to check how much propane is left

Use a scale

Look for the tare weight stamped on the cylinder collar, usually marked “TW.” The tare weight is the empty cylinder’s weight. Subtract it from the current scale reading:

Propane remaining = current total weight − tare weight

If the cylinder weighs 27 pounds and the stamped tare weight is 17 pounds, it contains approximately 10 pounds of propane—about half of its rated fuel capacity.

Use a compatible gauge

Inline pressure gauges can provide a broad indication, but cylinder pressure changes with temperature and does not fall in direct proportion to the liquid level. A scale is usually more useful when you need an actual quantity.

Do not use an open flame or unsafe test

Never test a cylinder with a match, lighter or other flame. Follow the appliance and cylinder manufacturer’s instructions for leak testing.

Ways to avoid running out during an event

• Check the fire table’s BTU rating and calculate the high-setting baseline.
• Weigh the cylinder before a long gathering.
• Use the lowest comfortable flame setting.
• Keep burner openings clean according to the manual.
• Use only manufacturer-approved wind guards and accessories.
• Keep a properly stored spare cylinder, but never place it under or next to the operating appliance.

To estimate runtime for your own appliance, find its maximum BTU-per-hour rating in the manual or data plate, then use the formula and table above. When comparing models, verify the fuel type, maximum BTU rating, required clearances, regulator and cylinder requirements with the manufacturer.

Propane cylinder safety

The Propane Education & Research Council’s portable-cylinder safety guide recommends keeping cylinders upright, closing the valve when the appliance is not in use, storing cylinders outdoors in a well-ventilated location and using only cylinders with an overfill-prevention device.

• Use the fire table outdoors and follow all required clearances.
• Inspect the hose, regulator, valve and connection before use.
• Perform the manufacturer-approved bubble leak test whenever a cylinder is connected.
• Keep combustible materials away from the table.
• Do not repair or modify the cylinder, regulator or appliance.
• Do not store a cylinder in a house, basement, garage, shed, tent or vehicle.

If you smell propane, hear hissing gas or see a visible vapor cloud, avoid flames and sparks, leave the area and contact the fire department or propane supplier from a safe location. Have the system inspected before using it again.

Frequently asked questions

How long does a 20 lb propane tank last at 50,000 BTU?

The calculated maximum-output runtime is about 8.6 hours. Actual runtime depends on the amount of fuel in the tank, control setting, weather and equipment condition.

Will a wind guard make the tank last longer?

A manufacturer-approved wind guard may make the flame more stable and reduce the need for a higher setting. It does not change how much energy the propane contains. Use only accessories approved for the specific table and maintain the required ventilation and clearances.

Does altitude increase propane-tank runtime?

Do not assume it does. Combustion and appliance performance can change with elevation, and some products require adjustment above a specified altitude. Follow the fire table manufacturer’s instructions.

Can I connect a fire table to a large home propane tank?

Only if the fire table manufacturer approves that configuration and the system uses the correct regulator, piping, pressure and fittings. Have a qualified propane professional perform the installation. Do not connect a portable appliance directly to a bulk tank without an approved system.

Can a propane fire table be converted to natural gas?

Only models specifically listed for conversion should be converted, using the manufacturer’s approved kit and instructions. Propane and natural gas use different pressures and orifices. A qualified professional should perform the work.

The planning answer: start with about 7–11 hours for a common 40,000–60,000 BTU fire table running at full output, then refine the estimate using your model’s rating and the actual pounds of propane in the cylinder.