Garage Heat Lab

BTU to Watts Converter

Formula: Watts = BTU/hr ÷ 3.412. Type a number to convert it, and see how much garage it would heat.

Watts

1,465W

As a heater, this delivers enough for about 120 sq ft of garage at average insulation on a 40°F rise. Check it in the garage heater calculator.

Convert the other way: Watts to BTU →

Updated

BTU/hr to Watts chart

BTU/hrWattsGarage it can heat
1,000 BTU/hr293.1 WUnder 50 sq ft
5,000 BTU/hr1,465 W120 sq ft
5,100 BTU/hr1,495 W120 sq ft
10,000 BTU/hr2,931 W230 sq ft
12,000 BTU/hr3,517 W280 sq ft
15,000 BTU/hr4,396 W350 sq ft
18,000 BTU/hr5,275 W420 sq ft
24,000 BTU/hr7,034 W560 sq ft
30,000 BTU/hr8,792 W700 sq ft
50,000 BTU/hr14,654 W1,170 sq ft
60,000 BTU/hr17,585 W1,410 sq ft
Garage area assumes average insulation, an 8 ft ceiling and a 40°F rise. Estimate only.

What this conversion means for a heater

Divide a BTU/hr rating by 3.412 to get watts of heat. For gas heaters, check whether the rating is input or output first: a 50,000 BTU gas heater at 80% efficiency delivers about 40,000 BTU/hr, or about 11,700 W of heat. Air conditioners and heat pumps move more heat than the power they draw, so this gives heat in watts, not electrical draw.

Ready to size a real heater? The garage heater calculator includes your climate and insulation.

Questions people ask

How many watts is 5,000 BTU?

About 1,465 W of heat or cooling. A 5,000 BTU air conditioner draws less electricity than that, because it moves heat rather than making it.

How many watts is 30,000 BTU?

About 8,792 W.

How do I convert BTU to watts?

Divide BTU/hr by 3.412. For example, 12,000 BTU/hr ÷ 3.412 = about 3,517 W.

What electric heater matches a 30,000 BTU propane heater?

At 80% efficiency a 30,000 BTU propane heater delivers about 24,000 BTU/hr, close to a 7,000 W electric heater.

Sources

Sources last checked October 31, 2026.

  1. EIA: British thermal units (accessed October 2026)