Hammer Curl vs Bicep Curl: The Grip That Changes Your Arms

The regular bicep curl (palms up) puts your biceps in the strongest position to curl the weight. It primarily targets the biceps brachii — the muscle that creates the "peak" when you flex.

The hammer curl (palms facing in) shifts work to the brachialis and brachioradialis ^[1]. The brachialis sits underneath your biceps and pushes it up when it grows, making your arm look thicker from the front. The brachioradialis is your main forearm muscle, which gives your arms that tapered look.

If you want taller, peaked biceps when you flex, regular curls are your best bet. They target the biceps brachii directly, which is the muscle responsible for that peak shape.

If you want thicker, wider-looking arms — especially when your arms are relaxed at your sides — hammer curls are the way to go. The brachialis adds width that you can see from the front, and the forearm development makes your entire arm look more complete.

Hammer curls are one of the best exercises for building your forearms. The neutral grip loads the brachioradialis heavily, which is the muscle that gives your forearm its shape when you look at it from the side.

Regular bicep curls do very little for forearm development. If your forearms are lagging behind your upper arms, hammer curls (along with wrist curls) should be in your program.

Hammer curls are almost always more comfortable. The neutral grip keeps your wrist in a natural position — the same position your hand is in when you hang your arms at your sides.

Regular curls force your palm to face up throughout the movement, which can strain the wrist, especially with heavier weights. If curls bother your wrists, switch to hammer curls. You'll still build great arms.