Patio Heater Sizes: Dimensions, Output and Coverage
Height, footprint and heat output of freestanding, pyramid, tabletop and electric patio heaters, how far the heat reaches, how long a propane tank lasts, and the space a heater needs around and above it.
A standard freestanding propane patio heater (the "mushroom" type) is about 87-91 in (221-231 cm) tall with a reflector 30-33 in (76-84 cm) across and a base about 18-21 in wide. It puts out 40,000-48,000 BTU per hour and warms seated people within roughly 6-9 ft of the pole. Tabletop models are 30-38 in tall at about 10,000-12,000 BTU; plug-in electric heaters are 1,500 W (about 5,100 BTU).
- Mushroom height
- 87-91 in (221-231 cm)
- Reflector
- 30-33 in (76-84 cm)
- Output
- 40,000-48,000 BTU/h
- 20 lb tank runtime
- About 9-11 h on high
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Patio heater sizes by type
Patio heaters fall into four families. The tall propane heater is still the most common; electric heaters dominate on covered terraces and restaurant patios.
| Type | Height | Footprint | Output | Fuel |
|---|---|---|---|---|
| Freestanding "mushroom" | 87-91 in (221-231 cm) | Base 18-21 in (46-53 cm); reflector 30-33 in (76-84 cm) | 40,000-48,000 BTU/h | 20 lb propane or natural gas |
| Pyramid / glass tube | 89-93 in (226-236 cm) | Base about 18-22 in (46-56 cm) square | 38,000-46,000 BTU/h | 20 lb propane |
| Tabletop | 30-38 in (76-97 cm) | Base 14-18 in (36-46 cm) | 10,000-12,000 BTU/h | 1 lb propane cylinder |
| Electric freestanding | 70-85 in (178-216 cm) | Base 15-20 in (38-51 cm) | 1,500 W (5,118 BTU/h) | 120 V outlet |
| Electric wall or ceiling bar | Bar 30-60 in (76-152 cm) long | Mounted 7-9 ft (2.1-2.7 m) high | 1,500-6,000 W (5,100-20,500 BTU/h) | 120 V or 240 V circuit |
One watt equals 3.412 BTU per hour, so a 1,500 W plug-in heater gives about 5,118 BTU/h, roughly an eighth of a 40,000 BTU propane heater. Electric infrared heaters still feel effective because they aim all their heat at people in front of them, but they warm a much smaller zone.
How far a patio heater's heat reaches
Patio heaters do not warm the air much outdoors. They radiate heat onto people and surfaces, so what matters is the distance from the heat source to the people around it.
| Heater | Comfortable distance | Area warmed | Typical use |
|---|---|---|---|
| Mushroom, 40,000-48,000 BTU | 6-9 ft (1.8-2.7 m) from the pole | Circle 12-18 ft across | Dining set for 4-6 |
| Pyramid, 38,000-46,000 BTU | 4-7 ft (1.2-2.1 m) | Circle 8-14 ft across | Seating group; more glow, less spread |
| Tabletop, 10,000-12,000 BTU | 3-5 ft (0.9-1.5 m) | The table and seats around it | Bistro or 4-seat table |
| Electric, 1,500 W | 4-8 ft (1.2-2.4 m) in front | About 6 × 8 ft in its beam | A couple of chairs, a corner |
Manufacturers' coverage claims are usually larger than these figures, which allow for evening temperatures around 45-55°F (7-13°C). Wind is the biggest factor: a steady breeze can halve the useful zone, and screens or walls on the windward side make a bigger difference than a larger heater.
Placing a heater for a dining set or seating group
- Size the seating zone first. A 4-seat dining set occupies about 10 × 10 ft including chair space (see the patio furniture space guide).
- Put the heater at the edge, not the center. A mushroom heater 2-3 ft beyond the table edge reaches the far chairs (about 7-8 ft away on a 48 in table) and keeps the pole out of the walkway.
- Add a second heater for zones longer than about 16-18 ft, or for groups that sit all round a large table, placing them on opposite sides.
- Keep the base out of paths. The 18-21 in base plus a 2-3 ft clearance ring means each heater takes a circle about 6-7 ft across that nobody should walk through with a tray.
- Check what is above. Umbrella canopies, awnings, pergola slats and branches must be well beyond the clearance printed on the heater. Close an umbrella before lighting a heater nearby; the patio umbrella guide lists canopy heights.
Clearances and safety
Gas-fired patio heaters in North America are certified to ANSI Z83.26 / CSA 2.37, and each one carries a rating plate with its minimum clearances to combustible materials above and to the sides. Those figures are part of the listing and vary by model, so use the plate, not a general rule.
- Above: tall heaters need open space well above the reflector, typically several feet. Under a standard 8-9 ft porch ceiling, a 7.5 ft heater has almost no room, which is why manuals for most freestanding propane heaters rule out covered areas.
- Sides: keep walls, furniture cushions, curtains, plants and umbrellas at least the side clearance on the plate, commonly 2-3 ft.
- Ventilation: propane and natural gas heaters are for outdoor use only. Never use one in a garage, tent, greenhouse or enclosed porch: they produce carbon monoxide.
- Wind and tipping: a tall heater has a high center of gravity. Most have a tilt switch that shuts off the gas if the heater tips; add weight to the base where the manual allows, and do not use one in strong wind.
- Tanks: store spare propane cylinders outdoors and upright, never indoors, as NFPA 58 and most fire codes require.
If the patio has a roof, look for a heater listed and installed for that location: usually a wall- or ceiling-mounted electric or natural gas infrared heater with a stated minimum mounting height and ceiling clearance. Do not bring a freestanding propane heater under a roof unless its manual explicitly allows it.
Propane runtime and electric circuit sizes
A 20 lb propane cylinder holds about 4.7 gallons. Propane carries about 21,548 BTU per pound, so a full tank holds about 431,000 BTU.
| Heater output | Runtime |
|---|---|
| 48,000 BTU/h (high) | About 9 hours |
| 40,000 BTU/h (high) | About 10.8 hours |
| 30,000 BTU/h (medium) | About 14 hours |
| 20,000 BTU/h (low) | About 21 hours |
A 1 lb cylinder (about 21,500 BTU) runs a 10,000 BTU tabletop heater for roughly 2 hours on high. For long evenings, tabletop models that accept a hose to a 20 lb tank are cheaper to run.
Electric heaters are sized by circuit:
- 1,500 W at 120 V draws 12.5 A, almost all of a 15 A circuit. A plug-in heater should not share the circuit with other heavy loads.
- Hardwired heaters are fixed space-heating equipment under the National Electrical Code, and the circuit must be sized for 125% of the load. A 1,500 W hardwired heater needs a 20 A circuit; a 3,000 W heater at 240 V (12.5 A) also needs 20 A.
- 4,000-6,000 W units at 240 V draw 16.7-25 A and need 25-40 A circuits. Have an electrician size and install them.
For a live flame rather than radiant heat, see the fire pit size guide and chiminea sizes. Heaters under a gazebo roof follow the same rules as a covered patio.
Frequently asked questions
How much area does a patio heater cover?
A 40,000-48,000 BTU mushroom heater keeps seated people comfortable within about 6-9 ft of the pole on a calm night, a circle 12-18 ft across. Makers often quote larger figures. Wind cuts the useful area sharply, so sheltered patios get far more from the same heater.
How tall is a patio heater?
Freestanding propane mushroom heaters are 87-91 in (about 7.3-7.6 ft, 221-231 cm) tall. Pyramid or glass-tube heaters are similar at 89-93 in. Tabletop heaters are 30-38 in, and wall-mounted electric heaters are short bars mounted about 7-9 ft high.
How long does a 20 lb propane tank last in a patio heater?
A full 20 lb tank holds about 430,000 BTU. At 40,000 BTU per hour on high that is about 10.8 hours; at 46,000 BTU it is about 9.4 hours. On a low setting the same tank can last 15-20 hours or more.
How many patio heaters do I need?
Plan one tall propane heater for each circle of about 12-18 ft, or roughly every 150-250 sq ft of seating area on a calm patio. A 12 × 16 ft patio with a dining set usually needs one well-placed heater; a 20 × 20 ft area needs two, placed on opposite sides of the seating.
Can I use a propane patio heater under a covered patio?
Only if the manufacturer's manual allows it and the clearances on the rating plate can be met, which a 7.5 ft heater rarely achieves under a typical 8-9 ft porch ceiling. Never use one in an enclosed space. Under a low roof, a mounted electric or natural gas heater designed for the location is the usual answer.