If you’ve got skinny arms and you’re tired of shirts hanging off your biceps like curtains on a stick, you’re not alone. A lot of guys struggle to put size on their arms, even when they’re hitting the gym regularly. But here’s the thing—just doing random curls a few times a week won’t get the job done.
To bulk up your arms, you need to hit both your biceps and triceps with intention. The biceps are the show muscles in the front, sure, but the triceps make up a bigger portion of your upper arm. So if you’re skipping them, you’re leaving size on the table. Combine the right exercises with solid nutrition and consistent training, and those skinny arms won’t stay skinny for long.
This guide breaks down five powerful exercises that actually work. No fluff. No nonsense. Just real, effective training for real results.
What’s Holding You Back?
Let’s be honest—most skinny guys aren’t eating enough, training heavy enough, or doing the right volume. You may be curling light dumbbells for 20 reps, but that won’t force your muscles to grow. You need progressive overload (lifting more weight or reps over time), and you need the right kind of stress on your arms.
Also, don’t forget recovery. Your arms won’t grow if you train them every single day with zero rest. They need time to rebuild and get bigger.
Now, let’s dive into the 5 best exercises to add serious size to your arms.
1. Barbell Curl
This is the king of biceps exercises. It’s simple, straightforward, and brutally effective. It lets you lift heavier than most other biceps movements, which helps build thickness and peak.
How to Do It:
- Stand tall with a barbell in your hands, palms facing up
- Keep your elbows tucked in to your sides
- Curl the bar up toward your chest
- Squeeze your biceps at the top
- Lower slowly under control
Sets/Reps: 4 sets of 8-12 reps
Why It Works:
Barbell curls hit both heads of the biceps and let you overload them with serious weight. This creates the kind of tension your muscles need to grow.
Tip: Don’t swing the weight or use your back. Keep it clean and controlled for the best results.
2. Close-Grip Bench Press
Most guys think of bench press as a chest exercise—and it is—but tweaking your grip turns it into a killer triceps builder.
How to Do It:
- Lie flat on a bench, grip the bar with hands shoulder-width apart
- Lower the bar to the lower part of your chest, elbows tucked in
- Push back up, focusing on extending through the triceps
Sets/Reps: 4 sets of 6-10 reps
Why It Works:
This movement lets you load your triceps with more weight than dumbbell kickbacks or triceps pushdowns. It’s a compound lift that builds real pushing strength and triceps mass.
Tip: Keep your form tight. Elbows should stay close to your body throughout the movement.
3. Hammer Curls
Hammer curls are like the secret weapon for thick arms. They target your brachialis, a muscle that lies underneath your biceps and adds real width to your upper arms.
How to Do It:
- Hold a dumbbell in each hand with your palms facing your sides
- Curl the dumbbells up while keeping your palms in a neutral (hammer) position
- Lower slowly under control
Sets/Reps: 3 sets of 10-12 reps
Why It Works:
Hammer curls work the biceps and forearms together, giving your arms that thicker, more solid look. They also improve grip strength.
Tip: Go slow on the way down. The negative part of the rep is where the muscle-building magic happens.
4. Overhead Triceps Extension
If your goal is sleeve-busting arms, this is a must-do. This move targets the long head of your triceps—the part that gives your upper arm that full, meaty look from behind.
How to Do It:
- Grab a dumbbell with both hands and lift it overhead
- Lower the dumbbell behind your head by bending your elbows
- Press it back up to the top position
Sets/Reps: 3-4 sets of 10-12 reps
Why It Works:
The stretch at the bottom of this move creates huge tension on the long head of the triceps. That deep stretch is what leads to big growth.
Tip: Keep your elbows in. If they flare out, you’re reducing the tension on your triceps.
5. Chin-Ups (Underhand Grip)
Bodyweight exercises often get overlooked when bulking up, but chin-ups are a killer mass builder for your biceps and upper back.
How to Do It:
- Grab a pull-up bar with your palms facing you (underhand grip)
- Pull your chin over the bar by engaging your biceps and lats
- Lower slowly until your arms are fully extended
Sets/Reps: 3 sets to failure
Why It Works:
Chin-ups hit your biceps hard, especially when done with control. They also build upper body strength and endurance. Add weight with a belt or backpack once bodyweight becomes too easy.
Tip: Don’t rush the reps. The slower the better when building arms.
Sample Arm-Bulking Routine
Here’s how you can structure your week to get the most out of these exercises:
Day 1 – Push Day (Triceps Focus):
- Close-Grip Bench Press
- Overhead Triceps Extension
- Chest and shoulder presses
- Core work
Day 2 – Pull Day (Biceps Focus):
- Barbell Curl
- Hammer Curl
- Chin-Ups
- Back rows and rear delt work
Day 3 – Rest or Legs
Day 4 – Arm Isolation Day:
- Barbell Curl – 4 sets
- Close-Grip Bench – 3 sets
- Hammer Curls – 3 sets
- Overhead Extensions – 3 sets
- Chin-Ups – 2 sets to failure
Day 5 – Rest or Light Cardio
Stick with this split for 6-8 weeks and focus on increasing the weight gradually while keeping good form.
What Else Helps Arms Grow?
Here’s the reality—if you want to bulk up your skinny arms, the exercises are just one part of the puzzle. You also need to focus on:
Eating for Muscle Growth
You can’t grow if you’re not eating enough. Aim for a calorie surplus with plenty of protein (at least 1.2-1.5 grams per kg of body weight), complex carbs, and healthy fats.
Sleep
Your muscles grow while you sleep. If you’re not getting 7-9 hours a night, you’re leaving gains behind.
Track Progress
Write down your sets, reps, and weights. Progressive overload is what builds muscle. If you’re lifting the same weights every week, your arms won’t change.
Be Patient
Skinny arms won’t transform in a week. But stay consistent, and within a few months, you’ll start filling out those sleeves with real size.
Final Thoughts
Building bigger arms isn’t about doing a thousand curls or buying some expensive pre-workout. It’s about hitting the right muscles with the right exercises, eating enough to support growth, and sticking with it long enough to see results.
Start with these five foundational moves. Focus on getting stronger, training smart, and staying consistent. If you do that, your skinny arms won’t stay skinny for much longer.
