How Many Patio Heaters Do I Need? A Simple Way to Count

The answer to “How many patio heaters do I need?” is usually one or two. Start with a tape measure and a walk around your patio. Look at where people actually sit. Infrared heaters warm the spot they point at, not the whole outdoor space. Count seating areas first and square feet second. We’ll walk you through the coverage figures for the patio heaters we sell and the sizing table below. We’ll also cover two mistakes that can leave you buying a third heater you did not need.

Step 1: count where people sit on the patio

Walk around and mark each seating group: the dining table, sofa corner, bar stools, and hot tub steps. Count each group as a zone. The rule of thumb is one heater per zone, aimed at the seats from about 8 feet up. A table and a lounge corner make two zones, so you need two heaters. That applies even if the patio is only 12 by 16 feet. A long narrow deck with one table is one zone. If you only use the table, buy one heater and aim it there. The empty half does not need heat.

Step 2: measure each zone in square feet

Measure each seating area. A dining table for six with the chairs pulled out is about 8 by 10 feet, or 80 square feet. A sofa and two chairs around a coffee table take closer to 10 by 12, or 120 square feet. Write down each measurement. To answer “How many patio heaters do I need?” you’ll match those areas to the coverage figures below. Measure the height from the floor to where the heater will hang, too. Bromic’s mounted heaters need about 8 feet from the floor to the bottom of the heater. The Detroit Radiant designer heaters hang 8 to 12 feet up. A 9 or 10 foot ceiling is easy to work with. A 14 foot ceiling needs a longer pole or a bigger heater.

Step 3: match a patio heater to each zone, electric, propane or natural gas

These heat output and coverage figures come from our product pages. Start with electric patio heaters in the middle column, then compare the gas options.

Take the 12 by 16 patio from step 1. With a table zone of about 100 square feet and a lounge zone of about 120, it takes two Cobalt 4000W heaters on electric. For gas, use one Tungsten 300 over each zone. A restaurant with a 20 foot row of tables takes one tube heater for the row. A small electric strip covers the host stand. Gas heaters cover more area per unit, which is the main reason to choose them for big open spaces. The electric models fit under lower roofs. They need an electrician and a 240 volt circuit rather than a gas line. Our gas vs electric patio heater comparison explains that choice.

Step 4: account for a covered patio, wind and cold

• Covered patio: A covered patio keeps the heat in, so the table figures hold. Mount the heater at the manufacturer’s height and it will perform as the product page says. Our advice on placing a heater under a covered patio includes the clearance numbers.
• Open deck with wind: Radiant heat is not blown away, but wind can affect the heater’s performance. Bromic rates the Tungsten gas heaters for wind up to 8 mph and the Platinum gas up to 12 mph. Detroit Radiant notes its designer heater loses performance above 3 mph. On a windy deck, go one size up or add a windbreak instead of a third heater.
• Cold climate: These heaters raise the felt temperature by a comfortable margin, not by 40 degrees. If winter evenings are near freezing, size for the top of each zone’s range. Plan on running the heater at full output.
• Tall ceiling: A heater 12 feet up covers less than the same heater at 8. Lower it on a pole or choose the next size.

The two mistakes that add a heater you do not need

One mistake is putting one big heater in the corner. You might choose the most powerful heater and hang it at the end of the patio, expecting it to reach every seat. Radiant heat drops off fast with distance. The near table gets too hot while the far sofa stays cold. Two smaller heaters, one over each zone, feel better and often cost less. The other mistake is mounting too high. A wall-mounted or ceiling heater on a 12 foot beam without a pole sends most of its warmth above people’s heads. Bromic makes poles in several lengths for this. You’ll find them listed on the product pages.

Quick answers: freestanding, propane and how much heat

• Do I need more than one outdoor patio heater? Yes, if you have more than one place where people sit. If you only have one table, you need one.
• Can one heater do a 400 square foot patio? Not well. For 400 square feet, use two gas heaters or three electric ones, each over a seating zone. One long tube heater is another option if the seating follows a straight run.
• Does a heater with two heat settings change the count? No, it changes the running cost. The Detroit Radiant two-stage models and the Bromic dimmer on the electric heaters let you hold a zone at low once it is warm. The Bromic dimmer is an add-on for electric heaters only. The Bromic gas heaters are on or off.
• What about a freestanding patio heater on propane? You need the same number of heaters. We sell two freestanding options: the Bromic Tungsten Portable on a 20 pound propane tank and the electric Eclipse Portable. Plan on a spare tank per heater for a party.

Questions people ask

How many patio heaters does an outdoor party or wedding need when it is 50 degrees out?

Count the places where guests will sit or stand for a while, and plan one heater per zone. Aim mounted heaters at seats from about 8 feet up. Near 50 degrees, size each zone at the top of its range and plan on full output all evening. Expect a comfortable boost in felt temperature, not 40 degrees. The Bromic Tungsten Portable uses propane, warms up to 215 square feet, and runs about 8 hours per tank. Its wheels and tilting head help you follow the party. Under a tent, keep overhead clearance and open sides for gas heaters. Blankets help guests who sit still.

How much room does a patio heater need above it under a roof?

Follow your exact model’s manual. The Bromic Tungsten and Platinum gas heaters need 8 feet from the floor to the heater bottom. With less than 42 inches above, add the Bromic heat deflector. The Platinum gas diagram shows 14 inches above with that deflector. The Bromic Cobalt and Tungsten Electric need 10 to 13 inches above. The Platinum Electric needs 8.5 inches on a ceiling mount. The Detroit Radiant designer gas heater needs 13 inches above to anything that burns, or 8 inches even under a ceiling that does not burn. The Detroit Radiant electric strips need 12 to 16 inches above.

Send us a photo and the two measurements, and we’ll tell you how many heaters you need and where to hang them. We offer free shipping on most brands (exceptions apply), no sales tax (except WY), and real people to talk to before you order. When you ask, “How many patio heaters do I need?” count the zones, measure them, and match a heater to each one.