The Best Way to Heat a Garage, Ranked for Your Garage

The cheapest way to heat a garage

On running cost alone, natural gas wins by a wide margin. Our default garage needs 24,500 BTU/hr. Heated 4 hours a day, 5 days a week for a 5-month winter, that is about $97 on gas, $152 with a mini split, $183 on propane and $266 on electric resistance heat.

Installation flips the picture when gas is not already at the garage. Add three winters of fuel to the installed cost and a 240 V electric heater lands at $1,549 to $3,049. Gas with a new line lands at $1,791 to $6,291. If a gas line is already there, gas drops to $1,291 to $4,291. Using the middle of each range, it then pays back its extra installation cost over ten winters at about 12 heated hours a week, or over three winters at about 39.

The answer changes when your prices do. Electricity runs well above the national average in some states, and propane prices swing with the season. Plug your own rates into the cost to run a garage heater page if your bill looks nothing like the average.

The best way to heat a garage with electricity

For a whole garage, a hardwired 240 V unit heater is the workhorse. Our default garage needs about 7,200 W, which a single 7,500 W heater covers on a 40 A circuit. A 120 V plug-in heater tops out at 1,500 W, about 5,100 BTU/hr. That is fine for a bench corner or a small, tight garage, and too little for most two-car garages in winter.

A ductless mini split is the efficient electric option. At the example COP of 1.75 we use (an editable assumption), it costs about $152 a winter against $266 for resistance heat, but it costs $2,400 to $5,500 installed. The electric garage heater guide covers watts, circuits and 120 V versus 240 V in detail.

The best way to heat a garage with natural gas

A vented gas unit heater hung from the ceiling is the usual answer. It blows warm air through the whole space, vents its exhaust outside and runs for about a third of the cost of electric heat per BTU at average prices. Our default garage calls for a 45,000 BTU/hr input unit.

Gas infrared tube heaters make sense in tall garages and shops where you work in one area. They warm people and the floor directly, so the space can feel comfortable at a lower air temperature. The natural gas garage heater guide covers sizing, venting and gas line work.

How to heat a garage without a heater

You cannot make heat from nothing, but you can need a lot less of it. In our model, insulated garage doors cut the default garage from 24,500 to 21,000 BTU/hr, about 14% less. Sealing air leaks around the doors and walls is worth about 12%. Holding 55°F instead of 60°F saves about 12%.

Those cuts shrink every heater option and every bill. On electric heat, insulated doors save about $38 a winter in our default case. Use the garage heater calculator and its Compare an upgrade panel to price the change against your own garage.

Free heat helps at the margins. Open the door on sunny afternoons, keep it shut on windy days and park a car that has just been driven inside. None of these will hold a cold garage at working temperature, but each one takes the edge off.

Heat and cool your garage with one system

A ductless mini split is the only common garage heater that also cools. ENERGY STAR specifically lists garages and other outbuildings as a good fit for ductless systems, since there are no ducts to extend.

The limit is deep cold. Heat pump efficiency and often output fall as the outdoor temperature drops; NREL gives the example of a COP of 2.5 at 32°F falling to 1.5 at 0°F. If your design low is near or below 0°F, check the model's rated heating output at that temperature before you count on it as your only heat.

Other ways people heat garages

Radiant floor heat

Tubing set into a concrete slab can give very even, comfortable heat. It is usually practical only when a new slab is being poured, and it warms up slowly, so it suits garages that stay heated all winter.

Wood stoves

Insurers summarizing the NFPA 211 standard say solid-fuel appliances should not be installed in garages or anywhere gasoline vapors are present. Check with your local code official and your insurer before you consider one.

Kerosene and diesel heaters

Unvented kerosene heaters release carbon monoxide, nitrogen dioxide and particles into the room, according to the EPA. They are a poor choice for a closed garage you spend time in.

Extending the house heat

The model residential code (IRC R302.5.2) says ducts in a garage must be sheet steel and have no openings into the garage. In practice that rules out adding a register from the house system in most places. Ask your local building department before you plan on it.

The best choice for how you use the garage

Workshop, now and then. At 55°F for 4 hours twice a week, gas costs about $34 a winter and electric about $93. The gap is too small to pay for a gas line, so electric is the better buy.

Workshop, most days. At 60°F for 8 hours, 5 days a week, gas drops to $194 against $532 for electric. Saving about $338 a winter, gas pays back its extra installation cost in a few winters when a line is already close to the garage.

Home gym. Short, warm sessions (62°F, 2 hours, 4 days) cost about $111 a winter on electric. Electric or electric infrared is the simple choice.

Storage or frost guard. Holding 40°F around the clock is a long-hours job: about $416 a winter on gas and $1,141 on electric in our default garage. Gas, or better insulation first, pays off fastest here.

Safety checklist

• Keep anything that can burn at least 3 feet from any heater, and plug portable heaters straight into a wall outlet, never an extension cord (USFA).
• Put a CO alarm in the home with any fuel-burning heater, and know the symptoms: headache, dizziness, weakness, nausea and confusion (CPSC).
• Gas appliances in a garage need their ignition source at least 18 inches above the floor unless they are listed as flammable-vapor-ignition resistant (IRC G2408.2).
• Have a licensed electrician add circuits and a qualified gas installer run gas lines and vents. Follow the heater's installation manual for clearances.