Best garage workshop heater

A heater has to replace the heat the garage loses. Loss depends on the area of walls, ceiling and door, the insulation, the air leaks and the gap between the temperature you want and the temperature outside. The garage heater BTU calculator does the arithmetic for your bay, and every constant on that page is labelled CONVENTION so you can see what was assumed.

Use the sizing pages for a quick read by bay: 12 x 20 one-car, 12 x 22 one-car, 20 x 20 two-car, 22 x 22 two-car, 24 x 24 two-car and 32 x 24 three-car. A bigger bay costs more than its floor suggests, because most of the loss is through the large door and an uninsulated ceiling.

Remember the conversion: one watt of electric heat is 3.412 BTU per hour. So a 1500W plug-in heater is about 5,100 BTU, the 3750W Dura Heat lists 12,800 BTU, a 7500W heater is about 25,600 BTU, and the gas units are labelled in BTU directly at 50,000 and 80,000. This page was researched from manufacturer listings, published specifications and owner reviews; the sizing is the calculator's, not a field measurement.

For a garage that also parks a car and stores gasoline, electric is the safer default. It has no flame, no exhaust and no fuel line, so it can sit near sawdust and a stray rag with fewer risks. The cost is the circuit. A 240V heater of any size needs a dedicated circuit, and the 240V circuit calculator returns the breaker and wire from NEC Table 430.248 style data. Heaters are not motors, so for a fixed heater the circuit is sized from the heater's own amps at 125 percent. Have a licensed electrician confirm.

Gas moves more heat per dollar of equipment and costs less per BTU in many areas, but it adds a flame, a flue or combustion air, and a gas line. In a woodshop gas is a poor idea whenever you are sanding or finishing, because fine dust and solvent vapor are ignition sources. In an auto or fab shop gas is a common choice, as long as the unit is hung where the manufacturer's clearances say. The comparison pages mini-split for a garage shop and the guide to using a garage as a workshop cover the third option, a heat pump, which is the quietest and often the cheapest to run.

The little Mr. Heater Buddy is a portable radiant propane unit, 9,000 BTU on its listing. It is popular for a quick warm-up, and its listing states the indoor-use conditions. Read them, keep it clear of anything flammable, and treat it as a heater for a ventilated space with a CO alarm.

Divide watts by volts to get amps. A 1500W heater at 120V is 12.5 A. A 3750W heater at 240V is 15.6 A. A 7500W heater at 240V is 31.25 A. Because a heater runs for hours, the NEC treats it as a continuous load, which is why the circuit is sized at 125 percent: about 19.5 A (a 20 A circuit) for the 3750W heater and about 39 A (a 40 A circuit) for the 7500W unit. Wire comes from NEC Table 310.16 at the 60 C column for NM cable: 12 AWG for 20 A and 8 AWG for 40 A. These are the figures the calculators use, and they are a starting point. Have a licensed electrician confirm the breaker, wire, receptacle and local code before any work.

The plug matters too. The InoKraft 7500W is listed with a NEMA 14-50 plug, the same receptacle used for an electric vehicle charger. A hard-wired unit like the Comfort Zone skips the plug. A plug-in unit can move if you change your mind; a hard-wired one is permanent. The 240V outlet install cost calculator estimates the job, and the Leviton 14-50 receptacle is the part for a plug-in setup. If the heater shares a panel with a welder or an EV charger, run the workshop amps calculator first.

In a garage that parks a car, the floor is for the car and the machines, so heat from the wall or the ceiling is better. A ceiling-mount unit like the Comfort Zone or the InoKraft heats downward and takes no floor. A forced-air gas unit hangs from the ceiling in a corner, aimed along the long axis of the bay, with the manufacturer's clearance to the wall and the ceiling.

Never place a heater where the car's hood or a parked ladder will block it. Keep the intake and outlet clear, and keep gasoline, solvents and rags well away. Do not run any heater on a long, thin extension cord; a 1500W unit on a bad cord is a common cause of garage fires. If you must use a cord, use a heavy one, such as the 10 gauge 50 ft cord, and read the voltage drop figures on the voltage drop calculator.

Insulate before you heat. A garage door with no insulation is the biggest single loss in most bays, and a kit such as the Reach Barrier single-door kit or the NASA TECH two-car kit is far less than a larger heater. Seal the door bottom and gaps, too. A smaller heater on a tight bay beats a bigger heater on a drafty one.

That depends on how many hours you work and how cold it gets. A heater that cuts a winter hobby from "too cold to stand" to "comfortable" is easy to justify. A heater that runs for ten hours a week all winter adds to the electric bill, and a heat pump is cheaper to run than resistance heat per BTU delivered. The question is a big one, and the plain answer is on the mini-split page: for a bay you use all year, a mini split costs more up front and less every month. For a bay you use a few weekends, a plug-in heater is plenty.

Two more notes. First, you rarely need to heat the whole bay to 70 degrees; heat the work spot, wear layers and let the room come up a little. Second, a heater is a good pair with insulation, because both reduce the BTU you need. Use the calculator before you buy, look at the circuit before you commit, and plan for a CO alarm and a smoke alarm in any garage where something burns.

Heat and a garage mix three hazards: fuel vapor, dust and electrical load. Gasoline vapor is heavier than air and collects at the floor, so a heater at floor level is the worst case; a heater hung high with a clear space around it is better. Fine wood dust is combustible, and a heater with a hot element or a flame near a dusty bench is a risk. And a heater is the heaviest steady electrical load in a garage, which is why the circuit must be dedicated.

Keep a fire extinguisher by the door. Test the smoke and CO alarms. Read the manual for your heater and follow it before anything on this page. These are general notes; this is not electrical, gas or fire-code advice, and local rules vary. Ask a licensed electrician or gas fitter before any work on a circuit or a gas line.