A therm is a unit of heat energy equal to 100,000 BTU (British Thermal Units). It is commonly used on US natural gas bills. One therm equals approximately 29.3 kWh of energy or roughly 100 cubic feet (1 CCF) of natural gas.

How many BTU are in a cubic foot of natural gas?

One cubic foot of natural gas contains approximately 1,030 BTU, though this varies slightly by gas composition. One CCF (100 cubic feet) contains approximately 103,000 BTU, which is close to one therm (100,000 BTU).

How do I convert therms to kWh?

Multiply therms by 29.3 to get kWh. For example, 50 therms × 29.3 = 1,465 kWh. This conversion is useful for comparing gas and electric heating costs.

Natural Gas Units: Therms, BTU, and Cubic Feet Explained

Natural Gas Unit Conversions

Unit	BTU	Therms	kWh	Cubic Feet
1 BTU	1	0.00001	0.000293	0.00097
1 therm	100,000	1	29.3	~97
1 CCF (100 cu ft)	~103,000	~1.03	30.2	100
1 MCF (1,000 cu ft)	~1,030,000	~10.3	302	1,000
1 kWh	3,412	0.0341	1	3.31

Average Gas Appliance Usage

Appliance	BTU/hour	Monthly Therms
Gas furnace	60,000-120,000	50-150
Gas water heater	30,000-50,000	15-25
Gas dryer	20,000-25,000	3-5
Gas range/oven	7,000-18,000	3-5
Gas fireplace	20,000-40,000	5-15

Comparing Gas vs Electric Costs

To compare: Gas cost per kWh = (Price per therm) ÷ 29.3

If gas costs $1.50/therm and electricity costs $0.15/kWh: gas = $1.50/29.3 = $0.051/kWh — gas heating is about 3x cheaper per unit of energy (though electric heat pumps can be 2-3x more efficient).

Convert energy units with our energy converter.