Kettlebells used to come in poods, a unit of measurement roughly equivalent to 35 pounds. Consequently, kettlebell buyers had a limited number of weight options to choose from. As the kettlebell's popularity has increased, so too has its versatility, and manufacturers now routinely offer kettlebells at a variety of weights. Because kettlebells are swung rather than lifted, you might need a kettlebell that is lighter than the weights you use for traditional lifts.
Variety of Sizes
Rather than buying kettlebells in a single weight, consider buying several different weights. Ballistic lifts -- such as cleans and snatches -- work better with heavier kettlebells, while grinds -- such as overhead presses -- typically require a lighter kettlebell. Try getting a kettlebell that's 5 to 10 pounds heavier for ballistic lifts and consider buying kettlebells in four to five weights so that you can alter the intensity of your workout and graduate to heavier weights as you develop strength.
Current Weightlifting Ability
If you're currently lifting weights, try a kettlebell that's about 5 pounds lighter than a dumbbell weight you regularly use and find challenging. Then, test the kettlebell by doing a few kettlebell swings. Swinging should be challenging, but should not be painful, and you shouldn't feel like you're going to drop the kettlebell at any moment.
Lifting the Kettlebell
When you test kettlebells at the store, try lifting them straight up as if you were doing a deadlift or bicep curl. The weight should not be easy to lift, but you should also not have to strain to pick it up. If you feel unbalanced or shaky, the weight is too heavy, but if picking up the kettlebell doesn't feel at all challenging, it's too light.
Kettlebells USA advises that men start with a kettlebell weighing between 35 and 44 pounds for ballistic movements and one weighing between 26 and 44 pounds for grinds. For absolute novices, the organization recommends going as low as 26 pounds for ballistic movements. It also emphasizes that women tend to pick kettlebells that are too light and recommends a weight between 18 and 26 pounds for ballistic movements and 13 and 18 pounds for grinding movements. Inactive, out of shape women can go as low as 9 to 13 pounds.