To determine what size grill you need, start by looking at the main cooking surface, which is measured in terms of primary square inches. A weekend griller of hamburgers and hot dogs will be fine with about 360 square inches (24 inches wide, 15 inches deep). A more adventurous griller or one with many mouths to feed will want a grill with at least 400 square inches. Grills can run up to more than 1,200 square inches (about 48 inches wide and 26 inches deep).
For a gas grill, the number of burners is also an important factor when considering size. Two burners is pretty standard; four is ideal if you grill often and five to six burners are perfect if you have a large family or you entertain often.
Primary burners are used for direct grilling.
Side burners are for pots or pans you might be using to heat or boil.
Back burners are reserved for rotisserie cooking.
If you add a warming rack to your grill, the cooking-or warming-space is called secondary square inches. This unit can be a quarter to half the size of the main cooking surface.
For each additional accessory you have, consider the space you'll be adding on, particularly when it comes to width. A side burner, infrared griller or wok cooker will add on at least another 15 to 24 inches of width per burner accessory.
Don't forget, grills typically need at least 2 feet of clearance on each side, a level surface to sit on and plenty of room for smoke to dissipate. They also shouldn't be placed under combustible construction — an eave or a breezeway — without a ventilation hood. These location requirements may affect the size of the grill you purchase.