Smith Machine vs Free Weights: Which Builds More Muscle?

What's the difference between a Smith machine and free weights?

On a Smith machine, the bar is attached to two rails. It can only slide up and down along that track, and you lock it in place by twisting it onto hooks along the rails.

Free weights are anything you hold and move yourself: dumbbells, barbells, kettlebells and weight plates. Nothing guides them, so your body has to control both the path of the weight and your balance.

You can do most barbell exercises on a Smith machine. Below are the common ones next to their free-weight versions. Tap an exercise name to see its starting position, movement and breathing step by step.

• Smith Machine Squat
• Barbell Squat
• Smith Machine Bench Press
• Bench Press
• Smith Machine Barbell Row
• Barbell Row

Which one builds more muscle?

Both build muscle, and about equally. When researchers pooled studies comparing machines (including the Smith machine) with free weights, muscle growth came out about the same.

So for building muscle, the equipment matters less than how you use it:

• Work hard enough. The last 1-2 reps of each set should feel hard. If your last rep felt as easy as your first, the weight is too light.
• Add weight or reps over time. If you lift the same weight for more reps than last time, or more weight for the same reps, you are making progress. See how many reps to do for muscle growth.
• Pick the one you'll keep doing. If the barbell feels intimidating and you keep skipping workouts, training on the Smith machine every week is the better choice.

Pros and cons at a glance

Neither is better at everything. Here is how they compare on the things beginners usually ask about.

Which should you use?

Pick by your situation, not by which one sounds more serious.

• You're new and nervous about the barbell: start with the Smith machine. You can learn the movement first without balancing a heavy bar.
• You're comfortable with the movement on the Smith machine: try it with a barbell. Balancing the weight yourself brings in the muscles that hold you steady, too. Start lighter than what you lifted on the Smith machine.
• You train alone: the Smith machine is the safer choice for heavy squats and bench presses. If you can't finish a rep, twist the bar onto a hook or lower it onto the safety stops. If you use a barbell, do it inside a rack with the safety bars set.
• Barbell squats bother your knees or lower back: try the Smith Machine Squat instead. The bar moves straight down along the rails, so you can put your feet a little forward and keep your back more upright as you sit down. If it still hurts, stop that exercise and get it checked.

You don't have to pick just one. You can also use both in the same workout.

How to use both in one workout

Do your free-weight exercises early in the workout, while you're fresh, and your Smith machine exercises later. When you're tired, it gets harder to balance the weight, and the rails keep the bar steady so you can finish your last sets safely.

Here is an example full-body day in that order. The reps are written as a range, such as 6-10. Start with a weight you can lift for the lowest number (6), and once you can do the highest number (10) on every set, add weight next time: the smallest plate on each side of a barbell or Smith machine bar (usually 2.5 lb), or the next dumbbell up.

• Barbell Squat
• Dumbbell Bench Press
• Smith Machine Bulgarian Split Squat
• Smith Machine Barbell Row

Frequently asked questions