BTU to kWh:
multiply by 0.00029307

How many kWh are in a BTU?

One British thermal unit (IT) is 0.0002930710702 kilowatt-hours. Put the other way, 1 kWh equals 3,412.141633 BTU. Both figures come from the same relationship, so you can use either one.

A BTU is a small amount of energy and a kilowatt-hour is a large one, which is why BTU values are usually in the thousands when you compare them with an electricity bill. The converter on this site uses the International Table BTU, written BTU (IT).

BTU to kWh formula and worked example

1. 1Note the energy in BTU.
2. 2Multiply by 0.0002930710702.
3. 3Round to two or three decimals, which is plenty for comparing bills.

Chart: BTU to kWh

These values are computed from the exact factor and shown without rounding, so you can scale them by moving the decimal point.

Using BTU to kWh for heating and cooling

Air conditioners, boilers and gas appliances are often rated in BTU, while electricity is billed in kWh. A rating of 12,000 BTU per hour, the common one-ton air conditioner size, is 12,000 × 0.0002930710702 = 3.5169 kW of cooling, so it moves 3.5169 kWh of heat every hour.

The reverse helps with gas and fuel comparisons. If a heater needs 2.5 kWh, that is 2.5 × 3,412.141633 = 8,530.35 BTU. Knowing both numbers lets you check whether a gas appliance really costs less than an electric one.

A second worked example and a quick estimate

Landlords and energy assessors use this conversion when they compare a gas boiler figure with an electric tariff. A furnace that burns 60,000 BTU of fuel energy has put in 60,000 × 0.0002930710702 = 17.58 kWh. An electric heater with the same input would be drawing 17.58 kWh from the meter.

Power ratings work the same way, as long as you keep the time part. A window air conditioner rated at 5,000 BTU/h is 5,000 × 0.0002930710702 = 1.4654 kW of cooling. A larger 18,000 BTU/h unit is 5.2753 kW, so it moves about 5.28 kWh of heat per hour.

A quick estimate for any BTU figure: divide by 3,400 and you are within about one percent of the real kWh value. For 2,500 BTU that gives about 0.735 kWh, and the exact answer is 0.7327 kWh. If your kWh answer comes out larger than the BTU figure, the factor has been inverted.

Turning a BTU figure into a running cost

To estimate a cost, convert the energy to kWh and multiply by your price per kWh. For 60,000 BTU the energy is 17.5843 kWh. At a tariff of 10 per kWh, that comes to about 175.84 in whichever currency your bill uses.

Remember that BTU is an amount of energy while BTU/h is a rate, like watts. A 12,000 BTU/h unit running for one hour uses about 3.517 kWh of heat, so the unit of time matters before you convert.

Common mistakes when converting BTU to kWh

• Mixing up BTU and BTU per hour. BTU is energy, BTU/h is power. Converting BTU/h gives kW, not kWh.
• Using the wrong factor. 0.00029307 is for BTU to kWh; 3,412 is for kWh to BTU. Swapping them is off by a factor of about 11 million.
• Assuming BTU always means the same thing. Several BTU definitions exist, so check which one a label uses. The site uses the IT value.
• Forgetting that heat output is not electricity use, as the tip above explains.