What Size Propane Heater Do I Need for My Garage?

When it comes to heating your garage, choosing the right size propane heater is crucial for ensuring efficient and effective heating during the colder months. To determine the ideal size of the propane heater for your garage, you need to consider several key factors, including the cubic feet of your garage, the desired temperature rise, and the British Thermal Units (BTUs) required.

Calculating the Cubic Feet of Your Garage

The first step in determining the size of the propane heater you need is to calculate the cubic feet of your garage. To do this, you’ll need to measure the length and width of your garage floor to obtain the square footage, and then multiply this number by the ceiling height.

For example, if your garage measures 20 feet by 30 feet, with a ceiling height of 10 feet, the total cubic feet would be:

20 feet x 30 feet x 10 feet = 6,000 cubic feet

This calculation will be essential in determining the BTU output required for your garage.

Calculating the Temperature Rise

what size propane heater do i need for my garage

The next step is to calculate the temperature rise, which is the difference between the coldest average low winter temperature in your area and the desired heated room temperature. This information will help you determine the BTU output needed to achieve your desired temperature.

For instance, if the coldest average low temperature in your area is 14°F and you want your garage heated to 68°F, the temperature rise would be:

68°F – 14°F = 54°F

Estimating the BTU Needs

To estimate the BTU output required for your garage, you’ll need to multiply the total cubic feet of your garage by 0.133, and then multiply that number by the desired temperature rise.

For example, if your garage has 6,000 cubic feet and you need a 54°F temperature rise, the calculation would be:

6,000 cubic feet x 0.133 x 54°F = 43,380 BTUs

It’s important to round this number up to the nearest thousand to ensure you have enough BTU output to effectively heat your garage.

Factors to Consider

When determining the size of the propane heater you need, it’s also important to consider the efficiency of your garage. A well-insulated garage will require less BTU output than a poorly insulated one, as it will retain heat more effectively.

Additionally, the number of doors and windows in your garage can also impact the BTU requirements. Garages with more openings will require a higher BTU output to maintain the desired temperature.

Recommended BTU Outputs

Based on the size of your garage, here are the recommended BTU outputs for propane heaters:

Garage Size Recommended BTU Output
One-car garage (4,000 cubic feet) 8,000 – 12,000 BTUs
Two-car garage (6,000 – 9,000 cubic feet) 30,000 – 50,000 BTUs
Three-car garage (9,000 – 12,000 cubic feet) 50,000 BTUs

Remember, these are general guidelines, and the actual BTU output required may vary depending on the specific factors of your garage, such as insulation, air leaks, and desired temperature.

By considering the cubic feet of your garage, the temperature rise, and the BTU output needed, you can ensure that you select the right size propane heater to keep your garage warm and comfortable throughout the colder months.


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  4. Lozier Heating & Cooling – The Best Garage Heaters and Why They’re Beneficial
  5. NewAir – How to Size Garage Heater