How long will a 20 lb propane tank run a fire pit?
A standard 20 lb propane tank — the grill-size cylinder — holds roughly 430,000 BTU of usable fuel. At a typical 60,000-BTU fire pit output that's about seven hours on high, and considerably more if you run the flame down low. A bigger burner drains it faster. That's the tradeoff of the portable tank: convenience today, but it will run dry.
The simple math
A full 20 lb cylinder carries just under five gallons of propane, and each gallon is worth roughly 91,500 BTU — so you're working with around 430,000 BTU of usable heat. Divide that by your burner's output and you have your runtime.
A 60,000-BTU pit on high uses close to that much per hour, so plan on the better part of an evening rather than a whole weekend. Turn it down to a low ambiance flame and the same tank can stretch to a couple of nights of shorter sittings. There's no cheating the physics — a hotter, bigger flame simply eats more fuel.
Why a plumbed line beats swapping tanks
The tank running out mid-conversation is the classic frustration with a portable fire pit. That's why so many WNC homeowners eventually have us run a permanent line — natural gas along the Asheville and Hendersonville mains never runs out, and out in Fairview, Candler, and Brevard a larger buried propane tank lasts a whole season instead of an evening.
On the coldest nights there's a second wrinkle: a small propane cylinder can lose pressure and even frost over in the cold as it works hard, which drops your flame. A larger tank and a properly sized line ride right through it.
Related questions
- How much does it cost per hour to run a gas fire pit?
- Where do you hide the propane tank for a fire table?
- Should I get a natural gas or propane fire pit?
- Can my home's large propane tank feed an outdoor fire pit?
- My house doesn't have natural gas service — can I still get a permanently plumbed fire pit with a dedicated propane tank?
- How much does it cost to install a gas fire pit?
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