The BTUs of Natural Gas Vs. Propane

Measuring British Thermal Units

• A BTU (British Thermal Unit) is the standard measurement for heat. It takes 55 BTUs to heat 1 cubic foot of space for an hour. To calculate a cubic foot, you multiply the length by the width by the height of a room. For example, a room that is 10 feet wide, 20 feet long and has 8-foot-tall ceilings, would have a cubic foot measurement of 1,600 cubic feet. As a result, that room would require 29.1 BTUs to raise the temperature by 1 degree each hour. Let's say that the temperature in the room is 60 degrees F and the desired temperature for the room is 68 degrees F. You would subtract the actual temperature from the desired temperature to determine how many degrees you need to raise the temperature, which in this case is 8 degrees F. That would require 232.8 BTUs per hour and a total of 5,587.2 BTUs over a 24-hour period.

Measuring Propane BTUs

• Propane is sold in gallons, and gallons can also be converted to cubic feet and then into BTUs. One cubit foot of propane contains 2,516 BTUs. Using the example of the 1,600-cubic-foot room, it would take a bit over 2.2 BTUs to heat the room each day to keep the room temperature at 68 degrees F.

Measuring Natural Gas BTUs

• The BTU equivalent for natural gas is 1,027 BTUs per cubic foot. To compare the number of BTUs that would be required for natural gas heating, let's use the same 1,600-cubic-foot room again. By dividing 5,587.2 - the total number of BTUs needed to heat the room for 24 hours - by 1,027 - the number of BTUs per cubic foot for natural gas - it would take around 5.4 BTUs of natural gas to heat the room each day.

Conclusion

• For a 1,600-cubic-foot room, it would take 150 percent more BTUs of natural gas to heat the room. However, while heating the room might take more natural gas than propane, the next consideration is whether that means it will cost more. Rates for natural gas vary from one municipality to another. Costs for propane gas vary too. Now that you know how to measure BTUs, you can check and compare local rates for natural gas and propane in your area to determine which makes the best choice for you.