Selecting dumbbells is a bit of a Goldilocks experience: Too light, and you won't give yourself the challenge you need. Too heavy, and you won't be able to complete your reps with proper form. So how do you find the perfect pair?
To find which size dumbbells to use, you'll need to consider the types of exercises you'll be doing with the weights. Pay close attention to your form and consult fitness professionals if needed.
Dumbbell Sets to Buy
The Best Dumbbells for Your Home Gym
Before purchasing dumbbells, there are a few basics you'll want to keep in mind. Dumbbells come in a variety of sizes and shapes. A single set of weights won't be too pricey, but the best size and style of dumbbells depends on your training goals.
Choose a Safe Weight
Not every set of dumbbells will work for each exercise. Chances are you can't do a biceps curl with the same weight you can deadlift.
Dumbbell exercises are also more unstable than barbells or machines, Cameron Yuen, PT, DPT, CSCS, physical therapist at Bespoke Treatments, tells LIVESTRONG.com, which is why the exercises feel more difficult.
But instability can also mean risk. "If you get injured, you can't train, so always think of safety first," Yuen adds.
"While you can use the barbell or machine weight you lift as a [benchmark], you should aim for 20 percent less when opting for a dumbbell," he explains. "This works well as a rule of thumb, but as you get more comfortable with the instability, you can go for heavier weights."
For example, if you squat 135 pounds total, you'll want to grab a pair of 50-pound dumbbells, which is about 20 percent less in total weight.
If you don't have a pre-existing benchmark weight from barbell or machine exercises, there are three general dumbbell weights that work well for upper-body isolation (like the biceps curl), upper-body compound exercises (like the chest press) and lower-body compound exercises (like the deadlift), Yuen says.
Generally, these weights are ideal for medium-rep ranges (10 to 15 reps) for most exercises.
Standard Dumbbell Weights
Form should always be your top priority when you're performing any kind of dumbbell exercise, Yuen explains. Toward the end of your sets, you should feel fatigued but not so much that your form breaks down.
If you aren't able to complete all of your reps with good form, consider smaller dumbbells. Or, if you could easily perform 2 to 3 more reps with good form, opt for heavier weights.
Select a dumbbell size that feels challenging but not impossible to lift for your desired number of repetitions. You should be able to finish all of your reps with good form. If you can't, choose a smaller size.
Consider Your Training Goals
Your training goals will largely decide what size dumbbells to use and purchase, especially if you don't want to buy several pairs. Consider the skill you'd like to hone: If you're lifting for muscle strength and size, the American College of Sports Medicine (ACSM) suggests doing 5 to 8 reps for 1 to 3 sets. In this case, you'll want to err on the heavier dumbbell side.
But if you're training for muscle endurance and tone, the ACSM recommends doing 15 to 20 reps for 1 to 3 sets. Lighter dumbbells are ideal for this rep range and set scheme.
You also want to consider the muscles you'd like to train and develop. Include some total-body exercises here and there, but if your goal is to improve your upper-body strength, you probably won't need 70-pound dumbbells.
Unfortunately, there isn't a one-size-fits-all approach to dumbbells, as each person starts at a certain level and has different goals. Before you purchase a pair (more on that below), make sure your weights are eligible for return or exchange if needed.
Shopping for Dumbbells
Today, you can find dumbbells in just about any size and form. While standard dumbbell sets are the cheapest option, adjustable dumbbells may be more practical, Yuen says.
"[Adjustable dumbbells] have come a long way in terms of design and ease of use, so if you're looking for a home set, I would choose one of these," he says. "The three target weights listed above work well as standard dumbbell weights, but as you get stronger you will probably want to challenge yourself with increased weight."