The Best Garage Heater for Your Garage Size and Fuel

The best garage heater for each garage

Each garage is heated from 20°F outside to 60°F inside, with an 8 ft ceiling unless noted. The electric column is the smallest common 240 V size that covers the need; the gas column is input BTU at 80% efficiency.

The 1-car garage needs only about 2,900 W, so a 4,000 W heater is enough; the King KB line below starts at 5,000 W. The shop needs about 76,500 BTU/hr, which no single electric garage heater supplies.

Best garage heater by fuel and how you use it

• A few hours a week, no gas240 V electric unit heater

  No vent and no fuel line; the install is one dedicated circuit. See electric garage heaters.

• Long hours or a cold climateNatural gas unit heater (vented)

  At 2025 U.S. average prices a delivered BTU from gas costs about a third of electric resistance heat. See natural gas garage heaters.

• No natural gas, still want gas heatPropane unit heater (vented)

  The same vented unit heaters run on propane from a tank. See propane garage heaters.

• One workbench, not the whole garageElectric infrared heater

  Warms you and the bench directly while the rest of the garage stays cool. Size one with the infrared garage heater sizing tool.

• Heat in winter, cooling in summerDuctless mini split heat pump

  Holds temperature cheaply but warms a cold garage slowly. Size one with the garage mini split calculator.

• Taking the edge off a small space120 V plug-in heater

  At 1,500 W it gives about 5,100 BTU/hr: fine for a bench, too small for a whole two-car garage in winter.

The best way to heat a garage guide ranks all six methods by what they would cost to run in your own garage.

Example models that match these sizes

These are examples of widely sold heaters in each size, with figures from each maker's own product page, checked November 7, 2026. They are not ranked and not tested by us. Models and part numbers change, so confirm the current spec sheet before you buy or wire anything.

Electric: King Electric KB series

A ceiling-hung, fan-forced 240 V unit heater line sold for garages and workshops. The coverage column is our estimate at average insulation, an 8 ft ceiling and a 40°F rise, not the maker's figure.

Vented gas: Modine Hot Dawg and Mr. Heater Big Maxx

Modine's Hot Dawg power-vented unit heaters come in 30,000 to 125,000 BTU/hr input sizes with a 3 in vent through 75,000, and Modine quotes thermal efficiency up to 83%. In our model the 45,000 BTU size covers a typical two- or three-car garage and the 100,000 BTU size covers a 30 × 40 shop. The Mr. Heater Big Maxx 50,000 BTU natural gas utility heater is a vented 50,000 BTU input unit; at 80% efficiency it delivers about 40,000 BTU/hr, enough in our model for a three-car garage or an uninsulated two-car garage.

Why maker coverage claims run high

Mr. Heater says the 50,000 BTU Big Maxx “heats up to 1,667 sq. ft.” Our model gives about 940 sq ft at average insulation and a 40°F rise, and 1,250 sq ft with good insulation. The maker's figure lines up with a well-insulated garage held only 30°F above outside, which works out to about 1,670 sq ft in our model.

Neither number is wrong; they answer different winters. Box coverage figures usually assume a mild climate and a tight building. Size from your own coldest temperature and insulation, which is what the garage heater calculator does.

What to check before you buy

• Output, not input. Gas heaters are labeled by input. Multiply by the listed efficiency, or 80% if none is given, before comparing with what your garage needs.
• Vented. For a closed garage, choose power-vented or separated-combustion gas units.
• Circuit. A 240 V heater needs a dedicated circuit sized at 125% of its current: the 7,500 W size draws about 31.3 A at 240 V. See the wire size calculator.
• Mounting height and clearances. The manual sets them, and gas heaters in garages need their ignition source raised off the floor.
• Thermostat. A built-in or wall thermostat keeps a garage at a low holding temperature instead of running flat out.
• Fuel version. Natural gas and propane versions are different; check for a factory model or approved conversion kit.

What to avoid

A ventless gas or propane heater as the main heat in a closed garage: the exhaust stays in the room. An oversized heater bought “to be safe”: it short-cycles and costs more to install. A 120 V plug-in heater for a whole two-car garage in a cold winter: at 1,500 W it supplies about 5,100 BTU/hr against the 24,500 BTU/hr a typical 24 × 24 garage needs. A heater sized from a car count alone: an uninsulated two-car garage needs about 37,000 BTU/hr, half again as much as an average one.