Freezing temperatures and short days can put a damper on wrenching, but a garage heater can keep the project fire burning all year round. Finding the best garage heater starts and ends with the size of your garage and where you live. One gearhead’s insulated garage in Kentucky is another’s drafty old pole barn in the California Sierra Foothills. Each requires a different type and size heater to bring the temperature up to a comfortable level for year-round quality shop time.
Calculating how much heater you’ll need depends first on your garage’s size, type, insulation, and location. The next consideration is what type of fuel hits the trifecta of cost, availability, and efficiency.
What works in our Science Barn might not work for you, so we tested several space heaters in various configurations. Read on and find out which type of heater is the best for your garage and how we found a new favorite portable powerhouse.
Best Garage Heaters Reviews & Recommendations 2021
About Our Garage Heaters Review and Roundup
New Englanders don’t dare rely on a single heat source in the home or the garage. Two heat sources and a backup is a good plan. We’ve tried more than a few heaters over the years, and this review features a mix of long used and recently acquired garage heaters in a variety of types and fuel sources. Mr. Heater bestowed us with Ambassador status and sent a few test units for evaluation. Even though electric resistance heat is not cost-effective, we picked up a few smaller 1.5kw electric heaters for comparison.
Two things that you should have in any garage, especially when you’re using a combustion fueled garage heater, are a carbon monoxide and smoke detector and a full complement of fire extinguishers. That said, finding the best garage heater hinges on a reasonably accurate calculation of how many BTU (British Thermal Units) you’ll need to turn a cold garage into a warm garage. It’s easy to convert BTU into kilowatt-hours, cords of firewood, or cold fusion reactor output afterward.
How Many BTU Will it Take to Heat My Garage?
For a rough estimate, figure on about 30-35 BTU per square foot for southern climates and 55-60 BTU per square foot for colder, northern regions. Using total cubic feet, desired garage temperature, and insulation level together makes for a more accurate number. Start with volume. Bust out the tape measure and multiply your garage’s width by its length to figure its total square feet. Multiply that number by the highest point in the ceiling for total cubic feet.
Next up is figuring your desired inside temperature vs. the outside temp. Warming a garage to 65 degrees from a winter freeze demands more BTU than just taking the chill out of a crisp spring morning.
Insulation is the last and most important factor. If your insulation won’t keep the heat inside or the cold out, you’re going to need more BTU. Rate your insulation from nonexistent (metal shed on a cement slab) to excellent (fully framed and insulated construction with raised floor) and factor that into your choice.
The Science Barn numbers worked out to 14,400 cubic feet, a temperature increase of 30 degrees (wishful thinking — ed.), and poor to nonexistent insulation. We plugged the numbers into six different online calculators and came up with wildly different BTU figures. We had estimates from over a million BTU (yikes!) to as low as 32,000. That’s why factors like insulation, flooring, and ceiling height are so important.
All six online calculations averaged and rounded down worked out to about 460,000 BTU. So we’ll go with that for our garage heaters review but remember: There are a lot of online BTU estimators, but your needs will vary depending on the space you’re heating and where it’s located.
Benefits of Garage Heaters
- 4-Season Wrenching. Taking time out for projects or hobbies is more crucial than ever, and a garage heater makes year-round enjoyment. Even a small 10-degree temperature increase can make a big difference in comfort.
- Climate Control. A permanently installed garage heater and thermostat can maintain constant temperature and humidity levels. Rapid temperature swings, excessive moisture, and repeated freeze-thaw cycles can damage valuable stored cars.
Types of Garage Heaters
Garage heaters use different fuels or configurations, but they fall into two types: convection and radiant. Convection heaters warm up the air; radiant heaters warm up surrounding objects. A steam radiator throws off a small amount of direct heat but primarily heats by convection. Radiant floor heating might warm up the garage floor a little — but it’s the convection that heats the surrounding air and keeps the room warm.
Convection heaters warm the air inside the building. Hot air rising from the heater creates a convection current that draws cold air through the bottom of the heater. Passive convection heaters may produce a little radiant heat, but the main advantage is quiet operation. Forced-air convection heaters speed up the process with a fan that draws in cold air in blasts out heat. Quick ramp-up and high BTU output make forced-air heaters a popular choice for shops and garages, but the combination of electric fans and combustion can sound like a J79 jet engine.
These heaters may also be called infrared and are available in permanent and portable styles. Radiant heaters are great for larger garages because they throw heat at you without having to heat up 15,000 cubic feet of frigid air around you. Portable propane tank top, reflective electric, infrared, and kerosene radiant heaters can quickly move with you for instant warmth. Permanent wall mount radiant heaters clear out floor space, and some come with blower fans for the best of both worlds. Hybrid units like our Mr. Heater kerosene-fueled radiant forced air heater take the combination approach.
Types of Garage Heater Fuel
Fuel cost and availability are essential factors in finding and running the best garage heater. We gathered up BTU figures for garage heater fuels from the United States Department of Energy and other sources, so use these for your calculations and run the numbers against your local fuel and utility rates for the total cost involved in warming up a cold garage. Wood BTU output will vary.
- One kilowatt-hour of electricity = 3,412 BTU
- One gallon of kerosene = 131,890 BTU
- One gallon of diesel fuel or home heating oil = 137,381 BTU
- One cubic foot of natural gas = 1,037 BTU
- One gallon propane = 91,452 BTU
- One pound of propane = 21,591 BTU
- One gallon of liquified natural gas = 82,000 BTU
- One pound liquified natural gas = 21,040 BTU
- One cord of firewood = 20,000,000 BTU
- One 40-pound bag of wood pellets = 320,000 BTU
- Permanent or Portable: Which setup is best for you depends on your garage layout, required BTU power, and how often you plan on wrenching in cold weather. Installing a permanent or stationary system can cost more initially, but deliver more long-term quality heat. Portables are great for occasional weekend garage excursions and spot heating.
Garage Heater Pricing
- Up to $100. Smaller electric space heaters in the 1-3kw range, some gas or kerosene portables, tank tops, and small radiant units fall into this category. Don’t expect anything more than direct personal heat.
- $100-300. More money brings more heating power with mid-range and high-output portables and some permanent shop heaters. Look for off-season closeouts in spring and summer to get the best deals on quality units.
- $300 and up. Now we’re talking. High-output portables that pack a fireball heating punch and even more powerful permanent installations as the numbers climb. Low-cost heaters with high operational fuel costs also belong here.
Best Garage Heaters Reviews & Recommendations 2021
Electric garage heaters are a safe and efficient choice for some garages, but a terrible idea for our Science Barn. Most electric heaters that pack enough power to heat our garage require a 240V outlet on at least a 30AMP circuit, and the 460,000 BTU needed to bring the Science Barn up 30 degrees works out to about 133,400 watts. Our wiring wouldn’t handle it and even if it could, the grid might not. We’d be run out of town.
The show must go on, so we picked up a few 1.5kw electric heaters for testing. Leaving out losses at the power generation source, an electric resistance heater is 100 percent efficient. What that means is all 1.5kw watt electric heaters should produce the same amount of heat. That said, it would take almost ninety 1.5kw heaters to warm up the Science Barn. Be skeptical of glowing recommendations for low wattage garage heaters.
We set the heaters up on a 600-cubic-foot enclosed porch. We ran each one for an hour from a 45-degree inside temperature starting point. The outside temperature varied from 33 to 35 degrees Fahrenheit. At the end of each hour, we recorded the inside temperature on the porch and aimed an infrared thermometer at the heater outlet.
Our results confirmed that 100 percent electric heater efficiency claim — and explained why some winter garage mechanics swear by electric heaters, while others swear at them. The smallest electric heater seemed like it was blowing hotter than the largest unit but at the end of the hour, the temperatures were essentially the same. Our electric heater testing lineup is shown below and the results run from left to right.
Best Mid-Size 1500w Electric Heater: Comfort Zone PowerGear Portable Ceramic Utility Heater
Comfort Zone packaged its 1500-watt ceramic heating element inside a rugged steel cylinder with high-impact plastic ends and a carry handle. Top-mounted controls for heat level and fan speed are easy to reach, and indicator lights for power and heat make it easy to see what’s going on. The adjustable steel tube stand was sturdy and stable.
It was 34 degrees outside and 45 degrees on the porch when we turned on the Comfort Zone. Heat ramped up quickly. The little blue barrel brought the inside temperature up to 65 degrees in one hour and measured around 200 degrees at the outlet.
Best Heavy-Duty 1500w Electric Heater: Mr. Heater Portable Forced Air Electric
If you need an electric heater for a small garage or workshop, this is your best bet. With an all-steel housing and adjustable steel tube stand, the Mr. Heater portable forced air electric convection heater was the biggest and toughest of the bunch.
It was 33 degrees outside and 45 degrees on the porch when we turned on Mr. Heater. The larger barrel diameter and quiet low-speed fan make it seem like there’s not much heat flowing from the outlet, but it’s there all the same.
The all-steel bruiser brought the inside temperature up to 64 degrees in one hour and measured around 200 degrees at the outlet. Mr. Heater also makes a more powerful 3.6 kW version that runs on 240V.
Best Compact 1500w Electric Heater: Multifun Portable Ceramic Heater
The smallest electric heater belted out heat that belied its size. Multifun wrapped up its 1500-watt ceramic heating element and fan in a steel housing with a carry handle. Rear-mounted controls were hard to see from the top, but the large toggle power switch and rotary heat control knob were tactile enough to operate out of sight. The front foot required some assembly with a few included screws and set the heater outlet back at an angle.
It was 34 degrees outside and 45 degrees on the porch when we turned on the Multifun. Heat ramped up immediately with a focused blast that brought the inside porch temperature to 65 degrees within the hour, with a 200-degree output temperature. For a small package, the Multifun packed a surprisingly effective punch of heat.
Featured Brands and More Heaters
What heats the Science Barn may or may not work for your garage, and while running an electric heater through a New England winter would lead to our financial ruin, a permanently installed or portable electric setup could be the best for you. Check out our featured manufacturer’s product lineups for a wide range of garage heater options. If it makes heat, they most likely make it.
With a heritage of innovation and quality that stretches back to 1872, Mr. Heater manufactures an extensive lineup of portable and permanent heaters for year-round indoor and outdoor comfort. The company is based in Cleveland, Ohio, and carries on the naming tradition of its fellow famous forest city brands Mr. Coffee and Mr. Gasket. From garages to golf carts. Mr. Heater is here to help.
Dyna-Glo manufactures an extensive line of consumer and commercial heaters for many applications. From portable forced air kerosene powerhouses to the direct warmth of wall mount radiant units, Dyna-Glo has a heater that can get the job done. The company also makes a range of gas, electric, natural and dual-fuel grills and smokers for the warmer months.
Master Climate Solutions is a division of the Dantherm group and manufactures permanent and portable heating and cooling solutions. The company’s mission is to create the best climate for work. Master makes heaters for everything from large commercial shops to one-car garages in a range of forced air torpedo heaters and radiant infrared units to electric fan heaters.
Garage Heater Tips
- Safety First: Never leave portable garage heaters unattended, and don’t cut corners on safety. Carbon monoxide is an odorless and invisible killer. Turn off combustion garage heaters before using flammable solvents such as non-chlorinated brake cleaners.
- Insulate Yourself: If garage insulation isn’t in your budget, investing in thermal underpants, insulated coveralls, mechanics gloves, and a winter hat can deliver excellent short term comfort and reduce garage heating costs.
Q: How many BTUs do I need to heat my garage?
Anywhere from 30-60 BTU per square foot depending on insulation level and climate zone. Total cubic feet, location, temperature rise, building type, material, and insulation are essential factors in calculating the required BTU. See our more detailed explanation above for an in-depth look at how to calculate BTU per cubic foot of garage space. Add 10 percent for far northern climate zones.
Q: Are outdoor heaters safe to use inside?
If you have to ask, then “No” is the best and safest answer. If your garage is more barn or lean-to than garage, then maybe — but follow local fire codes and take every possible safety precaution. Any form of combustion creates carbon dioxide and carbon monoxide. Always install carbon monoxide, smoke detectors, and automotive approved fire extinguishers before using any type of combustion garage heaters.
Q: Can I use diesel or heating oil instead of K1 Kerosene?
It depends on the garage heater. Some forced-air torpedo heaters have multi-fuel capability but may require adjustment and tuning for the best possible efficiency. Low-sulfur diesel fuel and heating oil are essentially the same, but K1 kerosene is best for wick heaters. Do not use K2, diesel, or heating oil in wick heaters.
Q: Will a heater work in an uninsulated garage?
It will definitely work a lot harder — but it probably won’t succeed. Uninsulated garages will require adding a lot more fuel to the fire. Factor insulation levels and building material R-values into your BTU calculations. Seal up as many drafts as you can and add more than a few BTU cushion to your temperature and cost calculations in colder climates.
Choosing the absolute best garage heater depends on a reasonably accurate calculation of the required BTU, the ideal type of heater for your garage’s size and layout, fuel costs and availability, climate zone, and what’s in the budget.