BTU ratings give you an idea of how much fuel a grill will burn per hour. The bigger the cooking area is, the higher the number of BTUs and the more fuel you will go through. Large grills with large cooking areas require more fuel and have higher BTU ratings. Small grills with smaller cooking areas require less fuel to achieve the same results and have lower BTU ratings. Evaluate based on heat flux, the amount of heat per square inch, to know the true efficiency and power of your grill.
Bottom line, when looking for a new gas grill, don’t let the BTU rating be the most important factor. Think of the BTU number as a fuel efficiency rating not how much heat the grill produces. Should you consider BTUs as one of the factors? Absolutely. Consider the total BTUs, the primary cooking area and the number of BTUs-per-square-inch. But don’t let that be the deciding factor in your purchase. Keep in mind that other factors like construction, heat retention and burner placement can all affect a grill’s performance. Look at all of the grill’s features, including the warranty, before making your decision.