Garage heaters by fuel

For BayHeat's standard 24×24 ft attached 2-car garage in Chicago, holding it at 55 °FSFrom a manual or spec sheetEXAMPLE_A_INPUT.targetTemp — lib/planner/fixtures.tsReport a problem costs about 470 /moCComputed by our enginecostsForSeasonalLoad() at IL pricesReport a problem on electric resistance and roughly 521 /moCComputed by our enginecostsForSeasonalLoad() at IL pricesReport a problem on diesel, in season. Your own garage and your own state's prices change both numbers — the calculator below runs them live.

Every fuel heats a garage the same way — it just prices the BTUs differently, and each one carries its own install rule and its own carbon monoxide risk. This page compares all six systems side by side at one worked example; the pages below cover each fuel's heater classes, clearances and safety conditions in depth. If you would rather pick by your situation than by fuel, see the best garage heater for each kind of garage. Heating a workshop instead of a garage? The shop heater guide matches 240V electric, vented gas and diesel to the circuit, flue or exhaust a shop has.

Which page you need

Fuel Cost Meter: every system, one garage, today's prices

This table runs the same 2-car garage, held at 55°F on a Chicago design day (the 99% design temperature), through all six systems at Illinois energy prices (2026-07 electricity; diesel is the Midwest regional average, 2026-09-21). The calculator re-runs this exact math against your garage's size and your own state's prices instead of Illinois' — the numbers below are one example, not a national average.

"Per hour, full output" is this garage's 31,900 BTU/hCComputed by our engineplan(EXAMPLE_A_INPUT).heating.qSizeReport a problem design load run flat out on the coldest day — a real winter runs mostly below that, which is what "per month" reflects. The portable radiant row's cylinder-exchange price is an estimate (about a dollar over bulk propane per gallon-equivalent) — exchange pricing isn't published state by state.

Buy: one representative heater per buyable fuel

A propane cylinder heater (the row above labeled portable radiant) is priced here for comparison only — it never gets a buy button on this site, attached garage or detached. See the propane page for why, and Can I run it? for the exact conditions on the ones that do.

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Cost per MMBtu isn't the whole decision

Electric resistance and diesel land close together per delivered BTU at typical Midwest prices — diesel only pulls ahead once electricity costs more than roughly 21¢/kWh, closer to California or New England rates than Illinois'. A mini-split beats resistance heat any month it stays above freezing, then loses that edge on the coldest nights. None of that changes the install rule: combustion heat needs a place for exhaust to go and a CO alarm. Electric heat needs a circuit sized for its nameplate, not just its price tag. For the natural gas row, the natural gas page covers sizing, venting and the gas fitter.

Safety scope