How Much Does It Cost to Heat a Garage?

Published October 2026 · 8 min read

Whether you're working on a car, running a woodshop, or just want to avoid frozen paint cans, heating a garage is one of the most common winter projects. It's also one of the easiest places to waste money. Here's what each fuel really costs, with the math shown so you can plug in your own prices.

How Much Heat Does a Garage Need?

Garages are usually the worst-insulated space in a home. A typical two-car garage (about 400 to 600 sq ft) can need anywhere from 15,000 BTU/hr if it's insulated in a mild climate to 40,000+ BTU/hr if it's uninsulated in a cold one.

Cost per Hour: The Apples-to-Apples Comparison

To compare fairly, here's what it costs to deliver 18,000 BTU of heat for one hour — the output of a Big Buddy on high or a medium garage heater — at typical 2026 U.S. prices.

Assumptions: national-average residential electricity of about 19¢/kWh (EIA, spring 2026), residential propane around $2.40–$2.70 per gallon (EIA), and natural gas around $1.50 per therm. Your local prices may differ significantly — check your utility bill. Real heaters cycle on and off, so actual hours of full output will usually be lower than the hours you spend in the garage.

The Math, So You Can Use Your Own Prices

• Electric: BTU ÷ 3,412 = kWh. 18,000 ÷ 3,412 = 5.3 kWh × your rate.
• Propane: one gallon holds about 91,500 BTU. 18,000 ÷ 91,500 = 0.2 gallons × your price per gallon.
• 1-lb cylinders: one cylinder holds about 21,600 BTU, so 18,000 BTU uses about 0.83 cylinders.
• Natural gas: one therm is 100,000 BTU. Divide by the heater's efficiency: 18,000 ÷ (100,000 × 0.80) = 0.23 therms × your rate.
• Heat pump: divide the electric figure by the coefficient of performance (COP). COP is typically 2–4 and falls as outdoor temperatures drop.

Which Option Fits Your Garage?

Occasional use (a few hours a month)

A portable propane heater is hard to beat — no installation, and the operating cost barely matters at low hours. Use a refillable 20-lb tank instead of 1-lb cylinders and you'll cut fuel cost by roughly 90%. Our Big Buddy vs. Little Buddy comparison helps you pick.

Regular weekend use

A 240-volt electric garage heater (typically 4,000–7,500 watts) is clean, quiet, and thermostat-controlled, with no combustion fumes. It costs more per hour than gas or propane, but there's no fuel to haul. Plan on an electrician to add a 240-volt circuit if you don't have one.

Daily use or a heated workshop

If you already have natural gas, a vented gas unit heater is usually the cheapest to run. If you don't, a ductless mini-split delivers heat at a similar cost — and cools the garage in summer. Both need professional installation.

Insulation First: The Cheapest Heat Is Heat You Keep

Before spending on a bigger heater, look at where heat escapes:

• Garage door: an insulation kit and new weatherstripping on the bottom seal are inexpensive and make a big difference.
• Walls and ceiling: many garages have bare studs. Insulating them can cut the heat you need dramatically.
• Air leaks: seal gaps around windows, the entry door, and where walls meet the slab.

Safety Notes

• Use a CO alarm with any fuel-burning heater, and follow its ventilation requirements. See our fuel heater safety guide.
• Keep heaters away from gasoline, solvents, sawdust, and paint fumes. Vented or electric heat is the safer choice for shops that use flammable materials.
• Plug-in 120-volt space heaters should go directly into a wall outlet — never an extension cord.