Freezers rage in size from 5 cubic feet to 25 cubic feet. Because chest freezers hold more food than equivalent sized upright freezers, a smaller unit might work for you. A smaller unit might be a requirement if your garage space is limited as chest freezers have relatively large footprints. However, the door opens up rather than out, so you don't need much clearance for cars and other large items you store in your garage.
Most chest freezers need to be defrosted manually. Although this keeps energy usage lower, you'll have to catch the water from melting ice. Choose a freezer that has a drain that releases the water through a hose. It's best if the drain is in the front of the freezer so you don't have to move the freezer when it's time to defrost it. Positioning the freezer so the drainage hose is within reach of your utility sink or garage door makes it easy to drain off the water without making a mess.
A freezer kept inside the house poses relatively few safety risks because you see it all the time. This isn't the case with a freezer located in your garage. Consider purchasing a model with a door lock to keep children out and ensure that the door stays tightly shut. You can also purchase a freezer with an alarm that sounds if an open door or other issue causes a significant change in temperature.
Because most garages aren't especially well lit, it's a good idea to purchase a freezer that has an interior light that's bright enough to illuminate food at the bottom of the chest. A model with drawers and baskets helps you keep large quantities of food organized. Finally, if it's possible that days or weeks might pass between visits to your freezer, purchasing one with a food-spoilage warranty that covers losses resulting from the freezer's malfunction could save you money if the freezer breaks down without you realizing it.