How will you use the blender? If you're looking to blend basic smoothies and shakes, there's no need to invest in a heavy-duty blender. Stick with an inexpensive, single-serve blender, or buy a cheap full-size blender, there are plenty out there. If you want to do a variety of tasks, and perhaps save having to buy another tool to do them, buy the best general use blender you can. If you're a serious from-scratch baker and want to grind grains to make your own flours or nuts to make nut butters, a heavy-duty blender will be your best friend.
Are you blending for a crowd -- or for one? Full-size blenders can hold anywhere from 5 to 9 cups. They're great for families or if you often blend drinks at parties. Single-serve blenders hold 2 cups or less, plenty if you want to blend one shake -- and you can drink straight from the blending jar, so there's less cleanup.
How often will you use it? If you plan to blend the occasional milkshake or batch of soup, experts say a good, inexpensive blender will suit you well. But if you use your blender on a regular basis, you'll be better off with a sturdier, more powerful model.
Where will you store it? The standard space between a kitchen countertop and the cabinets above is 18 inches. Most blenders are designed to be shorter than this, so they'll fit neatly on the back of the counter -- but a few are taller, notably the 20.5-inch Vitamix 5200. Consider the weight if you plan to store the blender in a cabinet; heavy blenders can be a chore to wrangle from an upper shelf, or lift from a lower cabinet.
Does your blender need to match your décor? If so, then color is a consideration for you; especially if you plan to store the blender on your countertop. Many blenders come in black or brushed-metal finish, while some manufacturers offer a rainbow of colors. .
Do you want the bonus features? Some extras add convenience and save time: a lid with a removable plug for adding ingredients while blending, and pre-programmed settings, such as "ice crush" or "smoothie," let you press one button and walk away -- the blender will run the cycle and stop itself.