Choosing the right propane tank for your fire pit is one of those details that seems minor until you run out of fuel 45 minutes into a dinner party. Tank size affects burn time, refill frequency, seasonal cost, and whether the cylinder fits inside your fire pit's base at all.
This guide compares the three main options: the standard 20 lb cylinder, the mid-size 30 lb tank, and bulk (100+ lb) stationary setups. If you are still deciding on a fire pit itself, start with our propane fire pit buying guide first.
How Propane Tanks Are Sized
Propane tanks are labeled by their water capacity weight, not the amount of propane they hold. A "20 lb tank" holds 20 pounds of propane when full, which equals about 4.7 gallons. One gallon of propane contains roughly 91,500 BTU of energy, according to the National Propane Gas Association (NPGA). That number is the foundation for every burn-time calculation in this article.
Here is how the three main tank sizes break down:
- 20 lb tank: The standard grill cylinder. Holds 4.7 gallons (roughly 430,000 BTU total). Weighs about 38 lb when full. Available at every hardware store, gas station, and big-box retailer.
- 30 lb tank: A step up. Holds 7.1 gallons (roughly 650,000 BTU total). Weighs about 54 lb when full. Less common at exchange stations but available at propane dealers.
- 100 lb tank (bulk): Stationary cylinder. Holds 23.6 gallons (roughly 2,160,000 BTU total). Weighs about 170 lb full. Stays in one place, connected to the fire pit via a longer hose and regulator.
For a deeper look at how BTU ratings drive fuel consumption, see our propane fire pit BTU guide.
Tank Comparison: Size, Burn Time, and Cost
The table below compares the three tank sizes side by side. Burn times assume continuous operation at a steady BTU output. Real-world results vary slightly based on ambient temperature, wind, and regulator efficiency.
| Spec | 20 lb Tank | 30 lb Tank | 100 lb Tank |
|---|---|---|---|
| Propane capacity | 4.7 gal (20 lb) | 7.1 gal (30 lb) | 23.6 gal (100 lb) |
| Total BTU | ~430,000 | ~650,000 | ~2,160,000 |
| Full tank weight | ~38 lb | ~54 lb | ~170 lb |
| Burn time at 40,000 BTU/hr | ~10.5 hours | ~16 hours | ~54 hours |
| Burn time at 50,000 BTU/hr | ~8.5 hours | ~13 hours | ~43 hours |
| Burn time at 60,000 BTU/hr | ~7 hours | ~10.5 hours | ~36 hours |
| Refill cost (approx.) | $15–$25 | $25–$40 | $70–$120 |
| Portability | Easy (one person) | Manageable (heavier) | Stationary only |
For exact runtime math on the most popular tank size, our 20 lb propane tank burn time guide walks through the calculation step by step.
The 20 lb Tank: Why It Is the Standard
The 20 lb propane cylinder is the default for a reason. It is the same tank used on gas grills across the country, which means refill and exchange locations are everywhere. Most propane fire pit tables are designed around this exact size, with a compartment in the base that fits the tank and hides it from view.
Advantages
- Universal fit: Nearly every fire pit table includes a 20 lb tank compartment. BALI OUTDOORS fire pit tables have a base panel that opens to a storage area sized for this exact cylinder.
- Easy refills: Hardware stores, gas stations, and exchange programs (Blue Rhino, AmeriGas) are everywhere. Most refills take under 10 minutes.
- Affordable: At $15–$25 per refill, the per-session cost stays low.
- Portable: At 38 lb full, one person can carry it from the car to the patio.
Limitations
- Shorter burn window: At 50,000 BTU, you get about 8–9 hours per tank. Heavy users refill every week or two.
- No mid-session refill: When the tank runs out, the flame dies. A spare 20 lb tank on hand is the simplest backup plan.
The 30 lb Tank: More Fuel, Fewer Trips
A 30 lb tank holds about 50% more propane than a 20 lb cylinder, translating to roughly 5–7 extra hours of burn time. For homeowners who entertain frequently, the longer interval between refills can be worth the tradeoff.
The Fit Problem
Here is the catch: most fire pit tables are built around the 20 lb tank footprint. A 30 lb cylinder is taller and wider, so it may not fit inside the base compartment. Before buying a 30 lb tank, measure your fire pit's internal storage dimensions and compare them against the tank specs (a standard 30 lb tank is roughly 24 inches tall and 12.5 inches in diameter).
If it does not fit inside, you have two options:
- External placement: Set the tank next to the fire pit with a longer hose. It stays visible unless you screen it with a cover or planter. For concealment ideas, see our guide on how to hide propane tanks safely and stylishly.
- Two 20 lb tanks instead: A pair of 20 lb cylinders gives you 9.4 gallons total (more than one 30 lb tank) with the bonus of a hot-swap when one runs empty.
Refill Availability
Exchange programs at grocery and hardware stores stock only 20 lb tanks. For a 30 lb refill, visit a propane dealer or full-service filling station.
Bulk Tanks (100 lb and Larger): For Heavy Use or Permanent Setups
If your fire pit runs several hours a day, multiple days a week, or if you also fuel a patio heater or outdoor kitchen from the same source, a bulk tank starts to make economic sense. A 100 lb tank delivers roughly five times the capacity of a 20 lb cylinder, and the per-gallon cost of propane drops when you buy in larger volumes.
When Bulk Makes Sense
- Permanent installations: Built-in fire pits connected to a dedicated propane line, with the tank behind a fence or inside a utility enclosure.
- Multiple appliances: One 100 lb tank can feed a fire pit, grill, and patio heater through a manifold or split regulator.
- Commercial or rental properties: Nightly fire feature use benefits from fewer refill interruptions.
Installation Considerations
Bulk tanks need a longer hose and a two-stage regulator. The U.S. Department of Transportation (DOT) and the NPGA publish placement guidelines, including minimum distances from buildings and property lines (typically 10 feet each). Work with a licensed propane dealer for delivery, placement, and connection. For ventilation rules around semi-enclosed patios, see our propane venting rules guide.
How to Calculate Your Ideal Tank Size
The formula is straightforward: Hours per tank = (Tank gallons × 91,500) ÷ BTU rating. Multiply that against your weekly usage to figure out refill frequency.
Example: A 50,000 BTU fire pit table running 3 hours, 3 nights a week (9 hours total). A 20 lb tank lasts ~8.6 hours, so you refill weekly. A 30 lb tank lasts ~13 hours, pushing refills to every 10 days. A 100 lb tank lasts ~43 hours, meaning roughly once a month.
If weekly refills feel like a chore, step up. If once a week is manageable, the 20 lb tank keeps things simple. For a broader look at ongoing fuel costs, see our propane cost guide for outdoor heating.
Safety and Transport Rules for Propane Tanks
Propane is a pressurized, flammable gas. Federal and state regulations govern how you store, transport, and connect tanks. Here are the basics:
Storage
- Always outdoors: Store tanks outside, upright, on a flat surface. Never in a garage, basement, or enclosed shed. The U.S. Consumer Product Safety Commission (CPSC) emphasizes this as the top safety rule.
- Away from heat: Avoid direct sunlight in extreme heat. Propane expands as temperature rises, and overfilled tanks can vent gas through the relief valve.
- Valve closed: Always close the tank valve when the fire pit is not in use.
Transport
- Upright and secured: Transport tanks standing up, never on their side. Secure them so they cannot roll during the drive.
- Ventilated vehicle: Use a truck bed or keep windows down. 49 CFR Part 177 restricts transporting propane in enclosed passenger compartments.
- Cap the valve: Place the dust cap over the valve during transport to prevent accidental release.
Leak Testing
Before connecting a tank each season, apply soapy water to hose fittings and valve connections. Open the tank slowly. Bubbles mean a leak. Tighten and retest. If bubbles persist, replace the hose or regulator.
If you are setting up a fire pit for the first time, our DIY propane fire pit installation guide covers the full connection process.
Which Tank Size Should You Pick?
For most homeowners with a standard propane fire pit table, the 20 lb tank is the right choice. It fits inside the base, refills are cheap and convenient, and a spare tank eliminates any worry about running out mid-evening.
Consider a 30 lb tank if it fits your setup (or you are comfortable with external placement) and you want longer sessions without swapping. Go bulk if you have a permanent installation, multiple propane appliances, or commercial-level usage.
Browse our full propane fire pit collection to find a table that fits your patio. Every BALI OUTDOORS fire pit table includes a built-in compartment for a standard 20 lb tank.
Frequently Asked Questions
Can I use a 30 lb propane tank on a fire pit designed for a 20 lb tank?
The gas connection is the same, so the tank will work with the same regulator and hose. The issue is physical fit. A 30 lb tank is taller and wider than a 20 lb cylinder, so it likely will not fit inside the fire pit's base compartment. You can place it externally and connect with a longer hose.
How do I know when my propane tank is almost empty?
Three methods work: weigh the tank and subtract the tare weight (stamped on the collar), pour warm water down the side and feel for the cold line where liquid propane sits, or install an inline gauge between the tank and regulator. The warm water method is free and takes about 30 seconds.
Is it cheaper to refill or exchange a propane tank?
Refilling is almost always cheaper. Exchange programs charge $20–$25 for a tank filled to only about 15 lb. A direct refill at a propane dealer costs $15–$20 for a full 20 lb fill.
How long does a 20 lb propane tank last on a fire pit?
At 40,000 BTU, roughly 10–11 hours. At 50,000 BTU, about 8–9 hours. At 60,000 BTU, around 7 hours. Actual results depend on wind, ambient temperature, and whether you run the burner at full or partial output. Our burn time guide has the full breakdown.
Can I connect two 20 lb tanks to one fire pit?
Yes, with a switchover regulator (automatic changeover valve). It connects two tanks and draws from the second when the first runs empty. You will need space near the fire pit for both cylinders.
Do propane tanks expire?
Tanks must be recertified 10 years after manufacture and every 5 years after that. The date is stamped on the collar. Expired tanks cannot be legally refilled until they pass inspection. Most dealers recertify on-site for $5–$15.
