How many watts is a 12,000 BTU air conditioner?

12,000 BTU/h of cooling is 3,517 W of heat moved — not the electricity it consumes, which depends on efficiency.

Does a 2 kW heater produce 6,824 BTU/h?

Yes. Electric resistance heating is essentially 100% efficient, so electrical input equals thermal output.

How do I size cooling for a room?

A rough guide is 100–130 W of cooling per square metre for a typical insulated room, which is 340–440 BTU/h per square metre.

Watts to BTU/h Converter | W to BTU per Hour

Conversion Formula

BTU/h = W × 3.412142

Multiply watts by 3.412142 to get BTU per hour, the power unit used in North American heating and cooling equipment ratings.

Complete Guide to Watts to BTU per hour Conversion

What is a Watts?

The watt (W) is the SI unit of power. In heating and cooling it expresses thermal output — how fast heat is added to or removed from a space.

What is a BTU per hour?

BTU per hour (BTU/h) is the North American measure of thermal power. Air conditioners, furnaces and heat pumps are all catalogued by it, usually abbreviated in marketing to just "BTU".

How the Conversion Works

One BTU is 1,055.06 joules, and one hour is 3,600 seconds, so one BTU/h equals 0.293 W. Inverting gives 3.412142 BTU/h per watt. The conversion applies to thermal power in either direction of heat flow — heating or cooling.

Why This Conversion Matters

Equipment sold in one market is specified in the other market's units constantly. Sizing a mini-split, comparing a European heat pump with a US one, or checking that a portable AC matches a room load all require this single conversion.

Scientific Context

Thermal output is not the same as electrical input for heat pumps and air conditioners, which move heat rather than generate it. A unit with a COP of 4 delivers four watts of heat per watt of electricity, so the BTU/h rating can be several times the power draw.

Step-by-Step Conversion Guide

Follow these steps to convert watts to btu per hour manually:

Start with your value in watts

Example: You want to convert 1000 W

Apply the conversion formula

Use the formula: BTU/h = W × 3.412142

Calculate the result

1000 W = 3,412.14 BTU/h

✓

Verify your answer

Use our calculator above to double-check your manual calculation.

Quick Mental Math Tip

Multiply watts by 3.412142 to get BTU per hour, the power unit used in North American heating and cooling equipment ratings.

Common Conversions

Watts to BTU per hour conversion table
Watts (W)	BTU per hour (BTU/h)	BTU per hour → Watts
100	341.2142	100 BTU/h = 29.3071 W
500	1706.071	500 BTU/h = 146.5355 W
1000	3412.142	1000 BTU/h = 293.071 W
2000	6824.284	2000 BTU/h = 586.1421 W
2500	8530.355	2500 BTU/h = 732.6776 W
3500	11942.497	3500 BTU/h = 1025.7486 W
5000	17060.71	5000 BTU/h = 1465.3552 W
7000	23884.994	7000 BTU/h = 2051.4973 W
10000	34121.42	10000 BTU/h = 2930.7104 W

When You'll Need This Conversion

Air conditioner sizing

Match a BTU/h rating to the watt-based heat load of a room.

Heat pump selection

Compare North American and European equipment on equal terms.

Server room cooling

IT equipment heat output is in watts; cooling equipment is rated in BTU/h.

HVAC training

Move between imperial and SI thermal power in load calculations.

Pro Tips for Accurate Conversions

One ton = 12,000 BTU/h = 3.517 kW

The three ways the same cooling capacity is written.

Heat load first, equipment second

Calculate the room load in watts, then shop for the matching BTU/h.

Oversizing hurts

An oversized AC short-cycles, dehumidifies poorly and wastes electricity.

Common Mistakes to Avoid

Reading BTU as energy rather than power

Product listings drop the "per hour" almost universally.

Air conditioner "BTU" ratings always mean BTU/h.

Assuming BTU/h equals electricity used

Heat pumps move more heat than the energy they consume.

Electrical input = thermal output ÷ COP.

Sizing by floor area alone

Insulation, glazing, orientation and occupancy change the load dramatically.

Use a proper heat load calculation, not a rule of thumb, for permanent installations.

History & Background

BTU/h became the HVAC standard through the American refrigeration industry, where cooling capacity was originally described in tons of ice melted per day.