BicepsDumbbellsBeginner

How to Do Hammer Curls

By Bryan Alger, Co-Founder of Gravitus

· Updated Sep 30, 2026

A hammer curl is a dumbbell curl with your palms facing each other for the whole rep. Keep your elbows at your sides and your wrists straight, and curl the dumbbells to your shoulders. It trains the biceps, the brachialis and the brachioradialis, the forearm muscle on the thumb side. Most lifters do 3 sets of 8 to 15 reps.

Sets x reps 3 x 8-15

Median 10-rep weight, per dumbbell 3516 lbkg men 209 lbkg women

Muscles Biceps, brachialis, brachioradialis

Grip Palms facing in

1Start. Stand tall with a dumbbell in each hand, palms facing your thighs and arms straight at your sides.
2Top. Keep your palm facing in and your upper arm still, and curl the dumbbell toward your shoulder. Alternating arms, as here, works the same way.

Watch 3 video demonstrations

Video 1 of 3

Find more video demonstrations in the Gravitus app

Technique

How to do a hammer curl

Stand tall with your feet hip-width apart and a dumbbell in each hand, arms straight and palms facing your thighs.
Pin your elbows to your sides and keep your wrists straight, thumbs pointing forward.
Curl the dumbbells toward your shoulders by bending only at the elbows, both together or one at a time. Your palms keep facing in.
Stop when your forearms are close to vertical, before your elbows start to move forward. Squeeze for a second.
Lower over 2 to 3 seconds until your arms are fully straight.

Grip

Palms in, up or down: what the grip changes

Most weightPalms inThe hammer curl. Your strongest grip, and a common pick when palms up bothers your wrists or elbows.

Most bicepsPalms up12% more biceps activity than palms in at the same effort, and slightly more brachioradialis.

Least weightPalms downA reverse curl. The biceps loses leverage, and Gravitus men log about a third less than on hammer curls.

Across the bodyCross-bodyPalms in, curling toward the opposite shoulder. The same muscles, and Gravitus men log about 7% less.

Grip changes how much the biceps can help, not which muscles work. At the same effort, palms up drew the most biceps and brachioradialis activity (Coratella 2023). Palms in is your strongest grip: in 11 men, elbow flexion force was 14% higher palms in than palms up, though the gap was not statistically significant (Kohn 2018).

Gravitus data

How much weight should you hammer curl?

On Gravitus, the median man lifts 35 lb (16 kg) per dumbbell for 10 reps on the hammer curl, and the median woman 20 lb (9 kg).

Men, typical 35 lb per dumbbell for 10 reps

Most lift: 27.5 to 45 lb
Top 10% lift: 55 lb or more
Starting out: under 27.5 lb

Women, typical 20 lb per dumbbell for 10 reps

Most lift: 17.5 to 25 lb
Top 10% lift: 30 lb or more
Starting out: under 17.5 lb

Men, typical 16 kg per dumbbell for 10 reps

Most lift: 13 to 20 kg
Top 10% lift: 25 kg or more
Starting out: under 13 kg

Women, typical 9 kg per dumbbell for 10 reps

Most lift: 7 to 11 kg
Top 10% lift: 14 kg or more
Starting out: under 7 kg

One-rep max / 10-rep weight, per dumbbell, rounded to 5 lb (2.5 under 40). From 20,100 men and 3,009 women who log the hammer curl on Gravitus, computed Sep 27, 2026 (Brzycki). Methodology
Percentile	Men	Women
25th	37.5 / 27.5 lb	22.5 / 17.5 lb
Median	45 / 35 lb	27.5 / 20 lb
75th	60 / 45 lb	32.5 / 25 lb
90th	75 / 55 lb	40 / 30 lb

One-rep max / 10-rep weight, per dumbbell, rounded to 2.5 kg (1 under 20). From 20,100 men and 3,009 women who log the hammer curl on Gravitus, computed Sep 27, 2026 (Brzycki). Methodology
Percentile	Men	Women
25th	17 / 13 kg	10 / 7 kg
Median	20 / 16 kg	12 / 9 kg
75th	27.5 / 20 kg	15 / 11 kg
90th	32.5 / 25 kg	19 / 14 kg

These are per-dumbbell weights. At the median, Gravitus men log about 5% more on hammer curls than on palms-up dumbbell curls, and women about the same.

Research

What the research says

The best test so far had 10 competitive bodybuilders curl their own 8-rep max with each grip. Palms up drew 12% more biceps activity than palms in and 6% more brachioradialis activity (Coratella 2023). The neutral grip in that study used a cable rope, not dumbbells, but no study we found shows the opposite result.

Four common hammer curl claims the research does not back:

Hammer curls work the brachioradialis more than regular curls. At the same effort it was slightly more active palms up (Coratella 2023). With no weight at all, it took a bigger share of the work palms down, but palms in and palms up did not differ (Kleiber 2015).
Hammer curls target the brachialis. The brachialis works in every curl. It attaches to the ulna, the forearm bone that does not rotate, so turning your palm does not change its leverage. An older study often cited for this had one volunteer rotating the forearm with the elbow held bent, not curling (Naito 1995).
Hammer curls hit the long head (or the short head). Both heads bend the elbow and turn the palm up. No study we found shows a neutral grip shifting work to either head, and the standard EMG electrode placement cannot tell them apart (Coratella 2023).
You can hammer curl far more than you curl. Gravitus men log about 5% more on hammer curls than on palms-up dumbbell curls, and women about the same.

Anatomy

Muscles worked

Biceps, long and short headBends the elbow and turns the palm up. It still works palms in, a little less than palms up.

Primary

BrachialisBends the elbow in any grip. Turning your palm does not change its leverage.

Primary

BrachioradialisThe forearm muscle on the thumb side. Helps bend the elbow in every grip.

Secondary

Forearms, front delts, coreGrip the dumbbells and hold your wrists, shoulders and torso still.

Stabilizer

Compare

Hammer curl vs dumbbell curl vs reverse curl

Attribute	Hammer curl	Dumbbell curl	Reverse curl
Palms	Facing in	Facing up	Facing down
Biceps activity	Palms up draws 12% more	Highest	Palms up draws 19% more
Brachioradialis activity	Palms up draws 6% more	Highest, by a small margin	Palms up draws 5% more
Weight men log	Baseline	About 5% less	About a third less
Best for	Most weight, sore wrists	Most biceps work	Variety

Verdict

Pick the palms-up curl for the most biceps work per set, and the hammer curl if palms up bothers your wrists or elbows. Both work the same muscles. Activity is not growth, and we found no trial that compared the two grips for growth, so rotating both across the week is a reasonable plan.

Programming

Sets, reps and progression

3Sets

8-15Reps

0-2Reps left

Stop each set 0 to 2 reps short of failure. Sets taken close to failure build muscle across a wide range of reps (Schoenfeld 2021), so pick a range you can keep strict.

A 5 lb (2.5 kg) jump is big on a light dumbbell. Add reps first: when every set reaches the top of your range, move up one dumbbell and drop back to the bottom of the range.

Form

Common mistakes

Swinging the torsoYour back and hips lift the weight, not your arms. Go a dumbbell lighter until you can stand still.
Elbows drifting forwardYour front delts take over and the top of the rep goes slack. Keep your elbows at your sides.
Wrists bendingKeep your wrist straight, with your thumb in line with your forearm, so your forearm muscles hold the dumbbell instead of your wrist joint.
Stopping short at the bottomIn a review of 11 trials, full-range and bottom-half training grew the biceps and brachialis near the elbow more than top-half partials (Kassiano 2023). Straighten your arms every rep.
Dropping the weightLower over 2 to 3 seconds instead of letting the dumbbells fall.

Variations

Hammer curl variations

Alternating Hammer CurlOne arm at a time. Easier to keep strict, but each set takes twice as long.

Seated Hammer CurlOn a bench with your back upright. Stops you using your legs and hips.

Incline Hammer CurlLying back on an incline bench, so your arms hang behind you and the elbow flexors work more stretched.

Cross Body Hammer CurlCurl toward the opposite shoulder. The same muscles with a little less weight.

Cable Rope Hammer CurlA rope on a low pulley. Palms in, with small weight jumps.

Hammer Preacher CurlUpper arm on a pad in front of you, palms in. Loaded at the bottom, where the standing curl is light.

Dumbbell CurlPalms up. More biceps activity at the same effort.

Zottman CurlCurl palms up, turn your palms down at the top and lower slowly.

FAQ

Questions people ask

What muscle do hammer curls work?

The biceps and the brachialis, with the brachioradialis helping. Your forearms, front delts and core hold you still.

Do hammer curls target brachialis or brachioradialis?

Both, as every curl does. The brachialis bends the elbow in any grip, and at the same effort the brachioradialis was slightly more active palms up than palms in (Coratella 2023). The hammer curl does not single out either one.

Hammer curls target which head?

Both heads of the biceps. No study we found has shown that a neutral grip shifts work to the long or the short head, and the biceps as a whole works a little less palms in than palms up.

Does hammer curl target forearm?

Yes, the brachioradialis, the forearm muscle on the thumb side near your elbow. It works about as hard in a palms-up curl. For the muscles that bend and straighten your wrist, add wrist curls or reverse wrist curls.

How high should hammer curls go?

Until your forearms are close to vertical, before your elbows move forward. Curling higher by lifting your elbows moves the work to your front delts.

Are hammer curls push or pull?

Pull. Your elbow flexors pull your forearm toward your upper arm, so hammer curls fit on a pull day with rows and pulldowns.

Is the hammer curl better than the bicep curl?

Not for the biceps or the brachioradialis. At the same effort, palms up drew 12% more biceps activity and 6% more brachioradialis activity (Coratella 2023). The hammer curl lets you use slightly more weight and suits lifters whose wrists or elbows complain palms up.

How much weight should I hammer curl?

For 10 reps, the median on Gravitus is 35 lb (16 kg) per dumbbell for men and 20 lb (9 kg) for women. The strongest quarter lifts 45 lb (20 kg) and 25 lb (11 kg) or more.

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References