How long will a standard 20-lb propane tank run my gas fire pit before it needs a refill?
A full 20-lb propane tank holds about 4.7 gallons — roughly 430,000 BTU of fuel — so it'll run a typical gas fire pit somewhere between 8 and 12 hours on medium, and as little as 6 to 7 hours wide open on a high-output burner like a 60,000-BTU pit. Turn the flame down and you'll stretch it considerably.
The math behind the number
A "20-pound" propane tank — the standard grill-size cylinder — holds about 4.7 gallons of propane when properly filled, and propane carries roughly 91,500 BTU per gallon. That's around 430,000 BTU of fuel in a full tank. To get your runtime, divide that by your fire pit's burner rating. A high-output pit like the Napoleon Uptown runs 60,000 BTU an hour, so wide open it'll drink a full tank in about seven hours. A more modest 40,000-BTU pit stretches the same tank to ten or eleven. The single biggest variable is you: run the flame low instead of maxed out and you can nearly double those numbers.
What shortens your real-world runtime
Those figures assume ideal conditions, and mountain evenings aren't always ideal. Cold matters most — propane pressure drops as the temperature falls, the tank can frost over, and on a genuinely cold WNC winter night a low tank may struggle to feed the burner at all. Wind is the other one: when it's gusty you tend to crank the flame up to keep it lively, which burns through fuel faster. And a tank is rarely truly full off the exchange rack. Plan for the low end of the range rather than the high end, especially in winter.
Never running dry mid-evening
The simple fix is a spare tank on hand. You can check a tank's level by weight — the empty "tare weight" is stamped on the collar (marked TW), so anything above that is fuel left — or add an inline gauge. But if you find yourself swapping tanks constantly, there's a better answer: if your fire pit sits near a home on a natural-gas main, like much of Asheville or Hendersonville, we can hard-plumb it to natural gas. No tank to refill, no running out, unlimited burn time. Running that [gas line](/services/outdoor-gas-line-installation) is licensed work, and it's our lane. Call (828) 545-0525.
Related questions
- Should I leave the propane tank hooked up to my fire pit between uses?
- How do I light a match-lit gas fire pit?
- Can I use my gas fire pit in the winter?
- What's the proper way to shut down a gas fire pit after using it?
- How do I winterize my gas fire pit at the end of the season?
- How do I light the pilot light on my gas fireplace?
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