Choosing a patio heater is mostly a fuel decision. Output, running cost, where you can put it and whether you can use it at all under a roof are all determined by what it burns — or whether it burns anything. Get the fuel right and the rest is styling.
One number frames the whole choice. A standard freestanding propane heater produces around 40,000 BTU per hour. A typical plug-in electric infrared heater on a 120V circuit produces about 5,100 BTU. That is not a small gap, and it explains why electric heaters feel excellent when you sit right under them and disappointing when you do not.
The three fuels compared
| Factor | Propane | Electric infrared | Natural gas |
|---|---|---|---|
| Typical output | 40,000 BTU/hr freestanding | 5,100 BTU/hr at 1,500W | 40,000–50,000 BTU/hr |
| How it heats | Heats the air around it | Radiant — warms objects and people directly | Heats the air around it |
| Effective radius | Roughly 10–15 ft in still air | Roughly 6–10 ft, directional | Roughly 10–15 ft |
| Runtime | 8–10 hours per 20 lb tank | Unlimited | Unlimited |
| Ongoing cost | Tank refills, the highest per hour | Modest, tracks your kWh rate | Usually the lowest per hour |
| Installation | None | Plug-in, or hardwired for larger units | Gas line by a licensed installer |
| Portable | Yes | Only within cord reach | No, fixed position |
| Wind tolerance | Poor — heated air blows away | Good — radiant heat is less affected | Poor |
| Use under a covered patio | Only with open sides and stated clearances | Yes, models rated for it | Only with open sides and stated clearances |
| Best for | Open patios, flexible placement, big groups | Covered patios, balconies, small seating areas | Permanent outdoor rooms used often |
The pattern is consistent. Propane buys flexibility, natural gas buys low running cost at the price of installation, and electric buys the ability to heat a covered or enclosed-ish space safely — but only for people sitting inside its cone.
Size it for your space in four steps
- Measure the area you actually want warm. Not the whole patio — the seating group. Length x width in feet.
- Apply the rough rule for open air: about 100 to 130 BTU per square foot for a mild evening, and up to 200 in cold or breezy conditions. A 12 x 12 ft seating area is 144 sq ft, so 15,000 to 29,000 BTU on a mild night.
- Adjust for exposure. Walls, screens or a pergola on the windward side can cut the requirement by roughly a third. See outdoor curtains and privacy screens and canopies, gazebos and pergolas.
- Consider two smaller units over one large one. Two heaters at the edges of the seating area give more even coverage than a single tall heater in the middle, which produces a hot ring and a cold centre.
Clearances and safety, not optional
Combustion heaters — propane and natural gas — consume oxygen and produce carbon monoxide. They are rated for outdoor use only, which means a space with at least two open sides. Never operate one in a garage, a fully enclosed tent, a screened porch with the panels closed, or under a low solid roof unless the manufacturer specifically permits it and you meet the stated clearance.
Typical clearances for a freestanding propane heater are 36 inches from any combustible surface at the sides and 24 to 36 inches above the reflector, but the figure on your model is the one that counts. Set the heater on a level, firm surface — a heater on soft ground or a sloped deck is a tipping hazard, and quality units include a tilt switch that cuts the gas. Store propane tanks upright, outdoors, never in a garage or basement.
For radiant warmth with fewer restrictions, or a different kind of evening entirely, look at fire pit season. The full heater range is in outdoor heating for cool nights and outdoor heating and cooling. When the season ends, cover and store the unit — see patio furniture covers and winterize your yard.
Common questions
Which fuel is cheapest to run?
Natural gas, once installed, is usually the lowest cost per hour, followed by electric, with propane highest. But installation for natural gas is a real expense, so the crossover point depends on how many evenings a year you use it.
Can I use a propane heater on a covered patio?
Only if the space has at least two fully open sides and you can meet the overhead clearance in the manual. If the roof is low or the sides are enclosed, choose electric infrared instead.
Why does my propane heater feel weak in wind?
Because it warms the air, and wind removes that air. Above roughly 10 mph, convection heaters lose most of their effect. Radiant electric or a windbreak on the upwind side is the fix.
How long does a 20 lb propane tank last?
Eight to ten hours on high for a 40,000 BTU heater. Keep a second tank if you host regularly — running out mid-evening is the common complaint.
Are electric patio heaters expensive to run?
A 1,500W unit uses 1.5 kWh per hour, so the cost is your electricity rate multiplied by hours. It is usually modest, and unlike propane there is nothing to refill or store.
Free US shipping on every order. Always read and follow the manufacturer instructions and clearance requirements for any heating appliance, and use combustion heaters outdoors only.
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