How Many Patio Heaters Do I Need?

Patio heaters are a great way to extend the use of your outdoor spaces even in the coldest of seasons.  Why should you end your outdoor events because of the cold? The heater units will provide enough warmth and that is when you wonder just how many are enough.

Several factors determine how many patio heaters will be needed to heat the space. An average of 1 or 2 heaters is enough for a standard patio. However, this may have to be increased or reduced depending on the considerations below. 

  1. Size of the Patio

This is the number one consideration and it comes as no surprise. The larger your space, the more heaters are needed to heat the air around to make the patio warm. People with small patios use just one heater unit.

A patio heater can comfortably heat a 1500-2000 square feet covered patio. What about the open patios? You will need a freestanding heater unit to cover a 20-foot diameter of space. 

Also, you may have to consider the power output in comparison to the area of the patio. The table below shows the patio areas with corresponding power outputs needed. 

Area of the patio (Square feet)BTUs for the Heater

Note that the table assumes the spaces are square. The heat radiates from the center from a freestanding heater outwards in a circle to other regions. So, the position of placing the heater is important. 

  1. BTU Output 

If you have a patio heater with low output, you will need to provide more for you to fully warm the area. There is a general rule of having one freestanding patio heater for approximately 1500 square feet of space. The table above explains how the BTU affects the number of heaters you will need with the size of the space.

  1. Positioning of The Heaters

There is a high likelihood that you may not need to heat the entire patio. This may lead to you getting many large heater units instead of using heaters for a targeted area. It will also help you save on costs relating to heating the space.

An example, you might want to place the heaters in areas of the patio that people mostly congregate. If you have two, you can place one at the seating lounge and the other near the dining set. Having targeted locations reduces the number of heaters compared to general heating.

People may get unsure of the exact position of the heaters. The solution is having a heater with wheels so that you can adjust the position to your comfort.

  1. Design of the Patio Heater

Various types of patio heaters have different ways that they can direct and radiate heat. For instance, a mounted heater unit is used to direct heat towards a quite small area. You will therefore need several of these units to cover the whole patio.

On the other hand, a freestanding patio heater radiates heat in 360⁰. The space around will be heated with varying efficiency levels. This will depend on the power output of the unit and the settings on the controller. It is, therefore, easier to use freestanding heaters in a large patio.

  1. Design of the Patio

For a covered patio, a single freestanding heater unit per 1500 square feet of space. Check on the BTU which should be high to provide enough heat. Remember to take caution with combustible items like cushions which should not be near the heater.

Uncovered patios often need more heater units compared to the covered ones as many factors affect the heat transfer. The heaters are mostly located in areas where people congregate or are heavily trafficked. The other factors named above will help you determine the number of heaters in such a situation.

  1. The Outdoor Weather Conditions

Change in seasons will affect the air temperatures and thus the heating process of patios. During winter, air temperatures will go very low and you will need more patio heaters to keep comfortably warm. You will also need more heater units on a windy night as the warm air is swept away fast.

Summer temperatures are high meaning you will have less effort of warming up your patio. In the tropical where the nights are warm, maybe one heater unit can be enough for a patio. You can add a heater if you still feel cold.


Determining the number of patio heaters will depend on your space and the readiness to spend. If you plan to invite many of your friends over to a large patio, you will have to add the number of patio heaters. It can be a challenging process but you will have to look at the factors above.

Remember to go for a heater unit that suits your patio needs rather than the aesthetics. The guide above will help you come up with the right quantity for your patio. When you can relax comfortably on the patio on a chilly night, then you made the right decision.