What Size Heater For 3 Car Garage

Want to find the best 3 car garage heater?

When choosing a garage heater, you want to make sure it is the right type and size for your space. Not all of these units are created equal, so it makes sense to go with one that provides the required heat output and saves energy.

In this review, you’ll find electric, propane, and natural gas garage heaters. What you choose depends on your preferred fuel source, but all of them have both pros and cons.

However, natural gas heaters are ideal for 3 car garages because they tend to have higher BTUs, are energy efficient, and heat the room cleanly.

Here is a comparison table of the best heaters for 3 car garage

What is the Average sq ft of a 3 Car Garage?

The average measurements of a 3-car garage are 24 by 36 feet. A garage with these dimensions will provide all the space that you need to fit three cars comfortably.

Besides, average-sized or even large-sized cars can comfortably fit in a garage that measures 24 by 36 feet.

You will also have enough extra space to store a few things and move about if your garage measures 24 by 36 feet. If you would like to convert a section of your garage into a small working area, it will be necessary to factor in this when deciding on the space.

Large garages can measure up to 24 by 40 feet. Such garages are ideal if for if you are keen on having a lot of extra space in the garage. One can use the extra space in the garage to store a few other items or even create a small working space.

On the lowest side, a 3-car garage may measure even 22 by 32 feet. Such small-sized garages can only store similarly small vehicles. You will also not have much room left in the garage once you park in your three small cars.

How Many BTUs Does It Take to Heat a 3-Car Garage?

The number of BTUs that you may need to heat a 3-car garage fully varies considerably. The following are some of the critical factors that determine the number of BTUs required to heat a garage.

  • Garages that are poorly insulated will need more BTUs than those which are adequately insulated. A lot of hot air is lost through the crevices of poorly insulated spaces. Therefore, one needs to account for the loss of heat by providing additional heating.
  • The temperature in your garage will vary depending on the seasons. In unusually cold seasons, you will need additional heat to maintain a comfortable environment inside the garage.
  • Your garage’s size is the most essential factor that determines the number of BTUs needed to keep the place warm and comfortable. The following is a brief breakdown of how you can use the size and other factors to determine the right number of BTUs that you need for the garage.

The first step of determining the amount of BTUs for properly heating a 3-car garage is to measure the space in square feet. If you have a huge square garage with the following dimensions: 40 by 40; then the area would be 1,600 square feet.

Next, divide the garage area by 200 and then multiply the result by 9000 to get the number of BTUs needed. You can adjust the factor of 9,000 either downwards or upwards. This decision depends on the level of insulation of your garage.

If the garage is properly insulated, then you can use a slightly lower figure. If the garage is not adequately insulated, use 9,000 to get the current number of BTUs needed to warm the space.

In our example, the number of BTUs needed to warm our large garage that measures 1,600 square feet would be 72,000.

If this is too much consider these heaters for 2 car garage.

What Type of Heater is Best for a Garage?

The best heaters for garages have features suitable for operating in harsh environments inside garages. Here are a few essential features that you should look out for when choosing the best 3-car garage heater.

  • Mounting option. Most garage heaters can be mounted either on the wall or roof. Some can be used as standalone heaters. If you are conscious of space, it would be wise to go for wall or ceiling-mountable heaters.
  • Power options. Unlike typical heaters used in indoor environments, garage heaters are rugged and have high power requirements. Most heaters designed for use in garages run on 220 to 240 volts. Luckily, garages have different wiring that allows for such devices to be installed and used.
  • Check the recommended clearance distances for any brands that you are interested in. Observing the recommended clearance distance helps to prevent instances of combustible materials in your garage from catching fire.
  • Safety features. The best heater for your garage has all the standard safety features, including overheat protection and a tip-over switch. Such features help to minimize the risk of injury and damages if anything goes wrong while you are using the heater.
  • Heaters with properly positioned manual control knobs, thermostats, and timers are relatively easy to control. You can personalize their performance base on the heating range and your preferences.

Where Should I Place my Garage Heater?

Garage heaters have recommended clearances. The safe distances are supposed to protect you and everyone else from possible fire outbreaks if the heaters come into close contact with combustible materials.

The clearance distances include measurements from the roof, walls, and even the floor. Always ensure that you follow the recommendations when installing the heater in the garage.

In addition to observing these distances, ensure that you do the following when positioning the heater.

  • Keep the heater facing your workstation and away from the garage door. Positioning your heater this way maximizes its heating performance by preventing unnecessary loss of heat through the door and other openings.
  • Ensure that combustible materials are nowhere near the heater. Fabrics, plastics, and papers can easily catch fire if they come into close contact with the hot surface of the heater.

Best 3 Car Garage Heater Reviews

1. Mr. Heater F260560 Big Maxx MHU80NG Natural Gas Unit Heater

Mr. Heater F260560 Big Maxx MHU80NG Natural Gas...
  • Your purchase includes One Mr. Heater Big Maxx Natural Gas Heater with 2 angle brackets & Liquid Propane conversion kit | Thermostat, hose & regulator not included
  • Heater dimensions – 29.33” L x 15.50” W x 26.37” H | Coverage area – 2000 Sq. Ft. | Performance – 80,000 BTU | Amps – 2.3 | Voltage – 120 V | Min 8 ft. clearance from floor to base of unit
  • For use with natural gas | Category 1 vertical, category 3 horizontal venting
  • Powered exhaust allows for vertical or horizontal venting | Spark ignition features self-diagnostic control module
  • This heater offers the operating versatility and safety that you have come to expect from Mr. Heater | Limited 3 year warranty on parts and burners

The Mr. Heater F260560 Big Maxx MHU80NG is a robust device with reliable performance. With a heating capacity of 80,000 BTUs, it can effectively warm spaces that are as large as 2,000 square feet.

Apart from the heating capacity, this gas ceiling heater has several other features that make it one of the best choices for warming, particularly drafty spaces such as garages. It features a high-velocity fan that powers the hot air across the entire space without causing much noise.

The automatic spark ignition system is ideal for helping you get the heater up and running instantly. Besides, you can always use the self-diagnostic control module to solve any technical faults that may occur.

The only significant drawback of using this heater is that you will have to purchase a regulator, thermostat, and hose separately. A thermostat is particularly crucial for helping you maintain the temperature in the garage within the desired range.


  • The heater can be vented vertically or horizontally
  • Powerful heating that is enough for up to 2,000 square feet of spaces
  • The heater comes with two brackets for easy installation


  • The heater is not sold with the hose, regulator, and thermostat

2. Modine HDS45AS0111 Natural Gas Hot Dawg Garage Heater

Modine HDS45AS0111 Natural Gas Hot Dawg Garage...
  • Natural Gas 45,000 BTU's 80% Efficient
  • For use where combustible materials are present (ie. Paint or Woodworking Shop)
  • Commonly used in 2 - 2.5 Car Garages
  • Separated Combustion: Fresh air intake and separate exhaust
  • Model: HDS45AS0111

One of the most notable features of the Modine HDS45AS0111 is the availability of right- and left-hand controls. One can easily use either form of control by merely flipping the heater over.

Also, you do not have to worry about carrying out time-consuming maintenance procedures if you install this heater. Its motor is permanently lubricated to save you the hassle of maintenance.

The permanent lubrication of the motor helps to keep the heater completely silent during operation.  Moreover, the use of the separated combustion design maximizes the safety level of this heater. You can comfortably use it in spaces that are full of highly combustible materials.

Although this heater is 80% efficient, its heating capacity is limited. The 45,000 BTU rating means that you can only use it to warm small to medium-sized spaces.

Nevertheless, if all that you are looking for is a heater that is powerful and energy-efficient heater for your garage, then you may as well settle for the Modine HDS45AS0111.


  • Safe for use in spaces with highly combustible material because of the separated combustion design
  • Great convenience because the heater has right and left controls
  • The heater requires low-level maintenance


  • Limited heating capacity of only 45,0000 BTUs

3. Dayton Electric Utility Heater

The Dayton Electric Utility Heater is ideal for use in domestic garages and related spaces. The heater uses the fan and forced-air heating system to provide reliable and full-room warmth.

Besides, you can effectively warm any part of your garage using this heater by merely adjusting its position and inclination angle. Spot heating can be a very reliable way of dealing with cold spots in particularly drafty spaces such as garages and workshops.

The inbuilt thermostat of this heater reads the temperature accurately. You can use it to program the Dayton Electric Utility Heater’s heating performance according to the requirements of your space.

Sadly, this heater has been designed for warming small-to-medium-sized spaces such as home garages. You can still use it for warming your 3-car garage. However, it will not serve you well if your garage is unusually large.


  • Powerful heating using the fan and forced-air method
  • The position and inclination of the heater can be adjusted to provide personalized heating
  • It is easy to control the performance of the heater using an inbuilt thermostat


  • Unsuitable for warming up large spaces

4. KING KB2410-1-B2-ECO KB ECO2S Garage Heater 

KING KB2410-1-B2-ECO KB ECO2S Garage Heater...
  • Built-In Fan Delay To Dissipate Heat
  • Remote Control & Universal Wall/Ceiling Bracket Included
  • Summer Fan Only & Timer Modes

One of the hallmarks of the KING KB2410-1-B2 is the built-in intelligent heating system. The system comprises several features that functionalities that help maximize the level of comfort without compromising the efficient utilization of power.

The two-stage heating system helps keep the heater’s operational costs down because it enables the heater to use the least amount of power.

Similarly, the built-in fan delay system helps to minimize energy consumption. The fan functions when one needs to dissipate heat according to the heating requirements of the room.

You can comfortably adjust the performance of your KING KB2410-1-B2 from a distance by using the universal remote control. When combined with the timer and thermostat, this control level can be harnessed into a highly user-friendly experience.

Although this heater comes with mounting brackets, installing it remains a highly technical process. The installation process may be daunting to you if you have minimal experience with a wall or ceiling-mounted heaters.


  • Provides an affordable method of heating when it is set in the eco mode
  • The heater has an intelligent heating system that helps to minimize power wastage and maximize comfort
  • User-friendly because of the included remote control


  • The installation procedure is highly technical

5. Mr. Heater F272700 40, 000 BTU Propane Garage Heater

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If you are looking for a heater that can provide warmth rapidly, it may be worth trying the Mr. Heater F272700.

The infrared heating system helps to raise the temperature in the room to the desired level within seconds. You will enjoy this heating mode if you need to warm a drafty and poorly insulated space like a garage.

Unlike other heaters that have powerful fans to dissipate heat, the Mr. Heater F272700 is a great choice if you are keen on the level of noise produced by your heater.

Although the lack of a powerful fan compromises the heater’s ability to spread warmth across unusually large spaces, you will nevertheless enjoy its performance if your space does not exceed 1,000 square feet.

This heater has one significant drawback: installing it is a very tedious process. It has recommended clearance distances that one must adhere to during the process. It may be wise to get the services of a certified technician to help.



  • Installing the heater is a tedious process because of the recommended allowances

6. NewAir G56 5600 Watt Garage Heater

NewAir Portable Heater (240V) Portable Electric...
  • [POWERFUL FAN FORCED HEATING] - With 5,600 watts of heating power, this electric garage heater packs a punch. It's strong enough to warm up to 600 square feet—perfect for a two-car garage or a 24x24 workshop or shed.
  • [RUGGED EXTERIOR BUILT TO LAST] - Black powder coated finish protects against scratches and scuffs, making this sturdy steel-bodied heater perfect for garages, workshops and light industrial environments. Alarm-No
  • [THERMOSTAT & AUTO-FAN TEMP CONTROL] - Set the temperature you want. Once the space has reached the ideal temperature, the fan will automatically kick-in as needed to keep your workshop warm. It’s that easy to get the heated working environment you need in winter.
  • [PORTABILITY FEATURES FOR FAR-RANGING HEAT] - Take advantage of 2 portable features: the cord wrap and carry handle. Together they make it easy for you to position or move your heater to the most ideal place in your garage, workshop, or shed.
  • [SAFETY FEATURES FOR PEACE OF MIND] - This UL-certified heater has an automatic shut-off function that prevents overheating. The outer construction stays cool after use to ensure safety for you and your space.

The inbuilt thermostat of this heater complements its broad heating range to provide highly customized heating. You can enjoy the convenience of adjusting the heater’s heating temperature anywhere from 45 to 95 degrees Fahrenheit.

This heating temperature range is broad enough to provide the right environment in colder spaces than average indoor rooms.

You do not need to worry about the danger of the heater overheating because of its features. The unique overheat protection feature helps prevent damages and even the occurrence of fires due to overheating.

Sadly, with a wattage rating of 5,600, this heater can provide warmth in small areas that do not measure more than 800 square feet.


  • The heater comes with the convenience of using a thermostat for controlling its performance
  • It has inbuilt features, including overheat protection
  • Highly durable because of the use of high-quality metals for its construction


  • It has a limited heating capacity

So, What is the Best Heater for 3 Car Garage

While you can use electric heaters to heat a garage as large as that of 3 cars, you’ll definitely experience a significant increase in your heating bills.

The most energy-efficient options would be forced air heaters and tube heaters.

The recommended heat output you need for a 3 car garage size is 60000 BTUs for forced air heaters or 50000 BTUs for tube heaters.

If you decide to go with electric heaters, don’t make them the primary source of heat. Use it to supplement the central heating system. If you don’t have central heat, try one of the two options.