Gas Log Fuel Calculator

Find out how much gas your gas logs (Natural Gas or Propane) will burn and how much it will cost to run them per hour.

Enter the BTU rating of your gas log set and then click the calculate button to find approximate cost.

An Overview

The amount of gas (Natural or Propane) that a gas log will use is directly related to the BTU rating of the burner system you choose. The BTU rating is in fact the amount of gas that is burned by the gas log set, not the amount of heat that the gas logs generate...particularly when referring to vented gas logs since much of the heat goes up the flue. Ventless gas logs will pretty much produce the same amount of heat in BTUs as the amount of gas that is consumed because they are burned with the damper closed and 99.9% of the heat comes into your room.

Many consumers do not know how to translate BTUs into either the amount of fuel used, or the cost associated with the BTUs.

BTU: BTU stands for British Thermal Units, which is a standard measurement of the amount of energy contained in any fuel that is released per hour that is burned. So a gas log set that has a 50000 BTU burner consumes 50000 BTUs of gas per hour.

Calculating the Cost to Burn Liquid Propane:

Liquid propane is normally sold either by the Pound or by the Gallon. So in order to make use of the BTU rating of a gas log to calculate the amount of propane gas it will consume and attribute a cost to that, we need to know how many BTUs there are in a pound or gallon of LP gas.

Using this information, you can easily calculate the amount of gas any gas log or gas appliance will consume.

Pounds of LP Gas Used: 40,000 BTUs divided by 22,000 BTUs = 1.818 Pounds
Gallons of LP Gas Used: 40,000 BTUs divided by 91,500 BTUs = 0.442 Gallons

If you know the cost per pound or gallon of your the LP gas that you purchase, simply multiply this by the calculated usage above. The calculation performed is based on the National Average for the cost of Propane Gas, which in fact varies widely by region.

The National Average cost of LP Gas is $2.536 per gallon according to the EIA as of Mar 2016.

Using this information, you are able to calculate the average cost in the USA to operate a 40,000 BTU gas log using this formula:

(The $2.536 average cost per gallon will vary. For example if the avg cost per gallon is 1.268 the cost would be $0.55 per hour.)

Calculating the Cost to Burn Natural Gas

Natural Gas is normally sold to the residential consumer by the Therm (100,000 BTUs) or Ccf (100 cubic feet = 102,700 BTUs). So in order to make use of the BTU rating of a gas log to calculate the amount of Natural Gas it will consume and attribute a cost to that, you can use these numbers to do the calculation.

With this information, you can take the BTU rating of a gas log and translate it into useable information by converting the BTUs into Therms or Ccf.

Therms of Natural Gas Used: 40,000 BTUs divided by 100,000 BTUs/Therm = 0.40 Therms
Ccf of Natural Gas Used: 40,000 BTUs divided by 102,700 BTUs = 0.389 Ccf

Find the cost of your natural gas in either Therms or Ccf by looking at your gas bill. If a different unit of measure is used, you will need to use a little additional math in order to perform the conversion properly. According to the EIA, these 2 units of measure are the most commonly used for by gas companies when billing residential consumers. So, take the cost/Therm or Ccf and multiply by the Therms or Ccf used by the gas logs found from the previous calculation above.

The National Average cost of Natural Gas is $1.095 per Therm according to the EIA 2016.

(The $1.095 average cost per therm will vary. For example if the avg cost per therm is 1.095 the cost would be $0.22 per hour.)

The National Average cost of Natural Gas is about half the cost of Propane. So if you have access to both fuels and are contemplating which to choose, then Natural Gas is likely your best choice.