A tank containing 20 pounds of propane provides approximately 8.6 hours of runtime on a 50,000 BTU/h fire pit table, or 7.8 hours on a 55,000 BTU/h model, running continuously at maximum input. Lower flame settings extend that time. A tank containing only 15 pounds of propane provides about 25% less runtime.
For a typical evening outside, that means several gatherings between refills. But before planning your next backyard get-together, check two things: how much propane is actually in your cylinder and how quickly your burner uses it.
Propane Tank Runtime at a Glance
The following estimates use approximately 21,500 BTU of energy per pound of propane.
| Continuous burner input | With 20 lb of propane | With 15 lb of propane |
|---|---|---|
| 30,000 BTU/h | 14.3 hours | 10.8 hours |
| 40,000 BTU/h | 10.8 hours | 8.1 hours |
| 50,000 BTU/h | 8.6 hours | 6.5 hours |
| 55,000 BTU/h | 7.8 hours | 5.9 hours |
| 60,000 BTU/h | 7.2 hours | 5.4 hours |
These are only estimates and do not guarantee burn times. They make the assumption of constant fuel use of the fuel input. Actual performance is subject to variations depending on fuel quantity, flame adjustment and operating conditions.
Also, the rating is an hourly fuel input rating. The higher the number, the quicker the propane is used at full power.
Check the Fuel Weight, Not Just the Tank Size
One quick tidbit that's easy to overlook: The 20-pound “20-pound tank” may not be filled with 20 pounds of propane!
The capacity of a cylinder is NOT the same as the contents of a cylinder. There are some exchange cylinders that have propane for 15 pounds. Be sure to review the label or inquire from the supplier about the amount of fuel that you are getting.
That difference matters. The theoretical 50,000 BTU/h is 20 pounds for 8.6 hours or 15 pounds for 6.5 hours.
It's not some magic number that has to be guessed. It's just that you began with less fuel.
How to Calculate Your Fire Table’s Runtime
Use this formula:
Estimated runtime in hours = propane weight in pounds × 21,500 ÷ burner input in BTU/h
For example:
20 × 21,500 ÷ 50,000 = 8.6 hours
Yardgrace’s propane fire table with side shelves is listed at 50,000 BTU. At that maximum input, a cylinder containing 20 pounds of propane provides roughly 8.6 calculated hours.
The 43-inch propane fire pit table is listed at 55,000 BTU. Using the same fuel quantity, its calculated full-power runtime is approximately 7.8 hours.
Those figures help compare fuel demand. They don’t tell you which table best fits your seating arrangement or how warm everyone will feel.
How Many Evenings Will One Tank Cover?
Hours are useful, but most people think in evenings.
If you usually sit outside for two hours after dinner, a tank lasts differently than it would during a five-hour party.
| Time per gathering | 50,000 BTU/h with 20 lb | 55,000 BTU/h with 20 lb |
|---|---|---|
| 2 hours | About 4 complete evenings | About 3 complete evenings |
| 3 hours | About 2 complete evenings | About 2 complete evenings |
| 4 hours | About 2 complete evenings | About 1 complete evening |
These counts assume maximum input throughout and round down to complete gatherings. There may be fuel left afterward, but don’t count on the last portion covering another full evening.
Why Your Actual Burn Time May Differ
Flame setting
Running a lower flame reduces fuel consumption. However, half a turn of the knob doesn’t necessarily mean half the gas flow.
If the manufacturer doesn’t publish lower-setting consumption, avoid promising a specific “low flame” runtime.
Wind and outdoor temperature
Wind can make the warmth feel less useful, encouraging you to increase the flame. Cold conditions can also reduce a cylinder’s ability to supply propane vapor, especially as it empties.
A weak flame therefore doesn’t always mean the tank is completely empty.
Other appliances using the same fuel
If you move one cylinder between a grill and a fire table, include both appliances’ operating time.
The same applies if you also use a propane patio heater. Each appliance consumes part of the available fuel; a tank used elsewhere won’t deliver the full fire-table estimate.
How to Check How Much Propane Is Left
Weighing the cylinder is a practical way to estimate remaining fuel.
Look for the tare weight, often stamped “TW” on the collar. This is the cylinder’s empty weight.
Remaining propane = total cylinder weight − tare weight
Suppose the cylinder weighs 29 pounds and its stamped tare weight is 17 pounds. It contains approximately 12 pounds of propane.
At 50,000 BTU/h, that gives:
12 × 21,500 ÷ 50,000 = approximately 5.2 hours
Check before guests arrive. It’s much easier than discovering an almost-empty tank halfway through dinner.
Ways to Make Each Tank Last Longer
Use the lowest stable flame setting permitted by the appliance instructions that gives you the experience you want.
Switch the table off when everyone heads indoors, following the manufacturer’s shutdown procedure. Keep a simple record of operating hours so you learn your own usage pattern.
Maintain the burner as directed and use only approved accessories. Don’t modify the regulator, restrict ventilation or add extra burner media to try to save fuel.
Frequently Asked Questions
How long does a 20 lb propane tank last at 50,000 BTU?
Approximately 8.6 hours at continuous maximum input, provided the cylinder actually contains 20 pounds of propane.
How long does a 15 lb propane tank last on a fire table?
At 50,000 BTU/h, approximately 6.5 hours. At 55,000 BTU/h, approximately 5.9 hours.
Will a tank last longer on low?
Yes, because lower fuel input extends runtime. The exact duration depends on the model’s actual low-setting consumption.
Can one tank last an entire weekend?
It can cover several shorter sessions. Add up your planned operating hours and compare them with the estimate for your fuel quantity and burner setting.
Does a larger tabletop use more propane?
Not automatically. Fuel consumption depends on burner input and operating setting, rather than tabletop dimensions alone.
Can I connect a larger propane tank?
Only if the manufacturer explicitly permits that cylinder and connection arrangement. Don’t assume a larger tank is compatible.
Should I heat a cold tank to improve performance?
No. Never apply external heat to a propane cylinder. Follow the appliance instructions if cold conditions affect operation.
What should I check before buying a fire pit table?
Check the maximum BTU/h input, approved cylinder size, tank placement, required clearances and flame controls. Together, these details help you plan both the patio layout and your refill routine.
