Watts to BTU

Watts to BTU Converter: Complete Guide to Converting Watts to BTU/hr

Converting watts to BTU/hr is the inverse of the most common HVAC calculation — and equally important. Electric heaters, infrared panels, heat pumps, and industrial equipment all rate power in watts, but HVAC specifications, building codes, and room-sizing guides in the US work in BTU/hr. A 1,500 W space heater = 5,118 BTU/hr. A 10,000 W electric furnace = 34,121 BTU/hr. Knowing this conversion lets you compare electric heat output with gas furnace ratings, select the right room size for a heater, and calculate energy costs across both unit systems.

The Exact Relationship: 1 W = 3.41214 BTU/hr

One watt equals exactly 3.41214 BTU/hr. This derives from the BTU definition: 1 BTU = 1055.06 joules. Since 1 watt = 1 joule/second = 3600 joules/hour: 3600 ÷ 1055.06 = 3.41214 BTU/hr per watt. Formula: BTU/hr = W × 3.41214.

Electric Space Heaters

Electric space heaters range from 750 W (2,559 BTU/hr) to 1,500 W (5,118 BTU/hr) to 2,000 W (6,824 BTU/hr). The rule of thumb for room heating is 10 BTU/hr per square foot — so a 1,500 W heater at 5,118 BTU/hr can heat approximately 512 sq ft. A 750 W heater handles about 256 sq ft. When comparing a 1,500 W electric panel heater to a 5,000 BTU/hr gas unit, the conversion reveals the electric unit provides nearly the same heat with the convenience of electricity.

Heat Pumps and Mini-Splits

Heat pump efficiency is rated as COP (Coefficient of Performance). A 2,000 W heat pump with COP 3.5 delivers 7,000 W of heat = 23,885 BTU/hr of heating capacity. This is why heat pumps outperform resistance heaters — the electrical watts consumed don't equal the BTU output when COP > 1. For mini-splits sold in kW (European market), a 5 kW unit = 17,061 BTU/hr of capacity.

Industrial and Commercial

Industrial electric heaters range from 5,000 W (17,061 BTU/hr) to 50,000 W (170,607 BTU/hr). Building codes often specify heat loads in BTU/hr even when equipment is electric. Converting 30 kW of electric heat: 30,000 × 3.41214 = 102,364 BTU/hr — comparable to a large gas furnace. Data centers specify cooling loads in BTU/hr; server racks consuming 10 kW generate 34,121 BTU/hr of heat that HVAC must remove.

How to Use This Converter

Enter any wattage to see BTU/hr instantly. Quick buttons cover 500 W to 10 kW — spanning most residential heaters and AC systems. The electric bolt visualizer shows lightning intensity proportional to wattage. The heat output radial gauge shows equivalent BTU/hr. The appliance panel compares your value against 4 common devices. All units display simultaneously: BTU/hr, kW, AC tons, kcal/hr, and horsepower.