There are no standard refrigerator sizes with respect to capacity or exterior dimensions. There is a steady gradient in size anywhere from 2 cu.ft. for a personal refrigerator to over 30 cu.ft. for a built-in model. The side-by-side refrigerators tend to be the largest, generally coming in capacities greater than 20 cu.ft. All other types can be found in a wide range of sizes.
Size and Efficiency
The first indispensible rule of thumb is: do not buy a refrigerator sized too small for your needs. When seeking out an energy efficient refrigerator it may be tempting to pick one with the lowest energy rating. But, if it does not meet your storage needs and you end up using an auxilliary refrigerator, that is a backwards step in both cost and efficency. Even if you expect to fill two 15 cu.ft. refrigerators with food, that would be less efficient than a single 30 cu.ft. refrigerator because two units contain a much greater surface area.
The second rule of thumb is: don’t just buy the largest refrigerator you can find. While larger refrigerators tend to have a better energy to size ratio, habitually cooling empty space is an unnecessary addition to the electrical bill and to the initial purchase price. Still, it is better to err on the larger side. A refrigerator sized 10 cu.ft. too large for your needs almost invariably wastes less energy than buying even the smallest auxilliary fridge or freezer.
Choosing Among Refrigerator Sizes
The best way to choose among refrigerator sizes is to make an assessment of your current refrigerator. Could you use maybe 25% more space? Or 25% less? If you do not know the storage capacity of your fridge, look up the model number on the sticker. Then enter it into the Energy Star website, which will give you the exact volume of your model.
The dimensions of your kitchen are of course important in choosing compliant refrigerator dimensions. When comparing room measurements to refrigerator dimensions, always tag on a couple inches to the sides and rear of the fridge dimensions. This will leave enough space for air to circulate around it, letting it run at optimal efficiency.