How Long Does a Gas Tank Last? Gas Fire Pit Heat Output Explained
Understanding Propane Burn Time and BTU Heat Levels for Gas Fire Pits
If you’ve just bought (or are thinking about buying) a gas fire pit, one of the first questions you’ll ask is:
“How long will my gas bottle last?”
The answer depends on BTU output, flame height, and bottle size, but the good news is we can calculate it accurately — and give you a clear chart to reference.
Whether you use your fire pit for quick weeknight ambience or long weekend gatherings, understanding how long your gas will last helps you plan ahead and avoid unexpected cut-offs mid-evening.
We’ll break everything down in simple terms, show you real examples based on popular gas fire pit models, and explain exactly how BTUs affect burn time. By the end, you’ll know which bottle size is right for your setup and how to get the most efficient performance from every tank.
Let’s dive in.
✅ What Affects Gas Bottle Life on a Fire Pit?
1. BTU Output (Heat Rating)
The higher the BTU, the more gas your fire pit burns per hour.
Most UK outdoor gas burners fall between 30,000–60,000 BTU.
2. Flame Height
Running your flame at full height can increase consumption by 25–40% compared to mid-level.
3. Gas Type
Most UK fire pits with gas use propane (LPG). Propane has excellent energy density, but still burns at a predictable rate per hour.
4. Bottle Size
Bigger bottles = more runtime, but also better gas pressure stability.
🔢 How to Calculate Fire Pit Gas Consumption
A 50,000 BTU fire pit burns approximately:
- ≈ 1.5 lbs/hr
- ≈ 0.68 kg/hr
This varies slightly, but this number gives a real-world estimate.
📊 Gas Bottle Runtime Chart (5kg, 10kg, 13kg)
Below is your custom-generated graph showing roughly how long each bottle lasts on a 50,000 BTU gas fire pit.
✔ 5kg LPG → ~7.3 hours
✔ 10kg LPG → ~14.7 hours
✔ 13kg LPG → ~19 hours
This includes typical flame modulation and pauses in real-world use (i.e., not constantly on full blast).
🧮 Runtime Table (All Bottle Sizes)
| Bottle Size | Approx. Runtime | Ideal For |
|---|---|---|
| 5kg | 6–8 hours | Small patios, occasional use |
| 10kg | 12–15 hours | Regular use, dinner parties |
| 13kg | 18–20 hours | Large fire pits, long evenings |
| 19kg | 28–32 hours | Heavy commercial or garden use |
| 47kg | 70+ hours | Permanent setups |
🔥 Real-World Example (Elementi Fire Pit)
A typical Elementi 50,000 BTU fire pit will get:
- 2–3 evenings from a 5kg bottle
- 5–7 evenings from a 10kg bottle
- 1–2 weeks casual use from a 13kg bottle
(Assuming 2–3 hours per session.)
🧠 Which Bottle Should You Choose?
🟩 5kg Bottle
Use when you need a compact, hidden solution. Great for indoor-looking outdoor furniture.
🟦 10kg Bottle
Best balance between size, weight, and runtime.
Most customers use this size with Elementi fire pits.
🟥 13kg Bottle
Perfect if you don’t want to refill often or you host long evenings around the fire.
🔥 Tank Cover Note:
Elementi’s large tank cover is designed to fit 5kg, 10kg, and 13kg LPG bottles, making it the most versatile option for any setup.
The small Elementi tank cover, on the other hand, is specifically sized to cover 5kg bottles only — ideal if you prefer a more compact footprint.
💡 How to Make Your Gas Bottle Last Longer
✔ Lower the flame height
Reduces consumption by up to 40%.
✔ Use a wind guard / windscreen
Wind will reduce flame stability & waste gas.
✔ Keep your fire pit clean
Blocked burners = inefficient combustion = more gas burned.
✔ Store your LPG correctly
Cold weather can reduce pressure and flame output.
✔ Upgrade to a larger bottle
Bigger bottles maintain pressure better and last much longer.