Enter your electric rate in decimal currency, i.e., $, €, £, etc. per kilowatt-hour (one cent = .01).
Be sure to add applicable taxes.   Find your rate
For example, if your electric rate is 9½ cents per kilowatt-hour, enter 0.095:
/kWh

Enter your cost of gas using the same decimal currency, i.e., $, €, £, etc.
Be sure to add applicable taxes. Select fuel and unit:
Natural gas per cubic foot Natural gas per 100 cubic feet Natural gas per cubic meter Natural gas per therm Propane per gallon Propane per liter Propane per pound Propane per kilogram

Enter your gas burner's efficiency rating (10-100%)*:
%                                                                

*Burner efficiency, numerically equal to output BTU divided by input BTU, will be specified on newer model burners.

• A non-vented gas space heater will be 99-100% efficient.
• A typical high-efficiency (condensing) vented central heating unit will be rated around 90-95%.
• Free-standing vented space heaters and older central units (non-condensing) will have efficiency ratings in the neighborhood of 70-80%.
• Oil to gas furnace/boiler conversions will typically be 50-75% efficient.
• Electric (resistance) space heating systems have an intrinsic efficiency of 100%.