How will you use the freezer? If the freezer is meant to supplement a too-small freezer compartment in your fridge, you may prefer an upright model that makes the contents much easier to see and access. If your goal is to buy meat in bulk and store it throughout the year, a chest freezer gives you more storage space for its size and uses less energy. Also, consider which features will be most useful to you. A safety lock is handy if you have small children who might leave the freezer open or climb into it. A quick-freeze feature, which can freeze large volumes of food quickly, can lock in the fresh flavor of garden produce; a soft-freeze zone is nice for keeping ice cream at a scoopable consistency.
How much room do you need? Freezers come in four basic sizes: compact (around 5 cubic feet), small (6 to 9 cubic feet), midsize (10 to 18 cubic feet) and large (19 cubic feet or more). The larger the freezer the more it costs to run, so don't buy more space than you can use. If you just want to store ice for parties, a mini freezer will give you plenty of room; if you want to store a whole side of beef, you'll need a midsize at least.
Where will the freezer go? Measure your space to see how large a freezer you can accommodate. Leave a few inches around the freezer for air circulation, as well as enough room to open the door. Also, check the path to and from the spot where you'll be moving the freezer and make sure that it can fit through doors and hallways.
If you plan to keep your freezer in an unheated area such as a garage, check the freezer's specifications to make sure it can handle the range of temperatures to which it will be subjected. In general, most freezers can handle temperatures between 32 degrees F and 100 degrees F. By contrast, if you plan to store your freezer in or near living areas, the priority becomes choosing a quieter model that won't drive you and anyone else in the house crazy with the noise of its compressor.
Are you okay with manually defrosting the freezer? Manual-defrost freezers run more quietly than auto-defrost models, won't dry your food out as quickly, and they're more energy efficient. However, if you let too much ice accumulate on the inside, they'll lose some of that energy efficiency. If you're not okay with the idea of manually defrosting your freezer any time more than a half-inch of frost accumulates inside -- usually about twice a year -- it's worth purchasing a model that automatically defrosts itself.
Will a freezer save you money? That depends on what model you choose and how you use it. As a general rule you should buy the smallest freezer possible, because empty space just means wasted energy and extra frost build-up. If you use the freezer regularly, it's easy to earn back the purchase price in savings by freezing extra garden produce, storing the catch from your hunting trips, buying meat and other groceries in bulk, or stocking up during sales. Another good strategy is to prepare big batches of food to freeze as a way to avoid less-healthy "convenience" foods.
Don't forget to include the yearly energy cost of operating the freezer. Most of today's top models cost between $25 and $50 per year to run, so you'll need to save an extra $3 to $5 off your monthly grocery bill in order to make up the purchase price.