The characteristics of gas cooktops are generally rated in BTUs or British Thermal Units/hour. This is just another way of expressing the conversion of energy into heat. While it is true that a 12,000 BTU burner will convert energy at a faster rate than a 9,000 BTU unit, there are several other factors that can affect burner performance. The size of burner and the distance from the burner to the cooking vessel can affect how well the heat energy is transferred to the cookware. Ventilation and drafts can also affect the way this heat is transferred and finally, sealed burners can change the energy transfer rate. If all cooktop burners were the exact shape and size, BTUs would be an accurate comparison of the burners performance, but these factors make it difficult to use BTUs as a direct comparison of efficiency between various units.

The temperature that a burner produces is a direct result of the burners design, including the cap, jets and grate. The ability of a burner to maintain a constant specific temperature is equally as, if not more important than the BTU capabilities of the burner. The range of temperatures a burner can produce, and how well it can maintain them, will be the result of both factors: BTUs and overall design. This is why you will often see both ratings used in cooktop specifications.