How To Grow Arm Muscle: Avoid These 6 Mistakes Which I Made As A Skinny Dude!

how to grow arm muscle

Have you got skinny arms? Are you hoping to pack some serious mass onto those arm muscles? Then stick around. Because today, I will be explaining how to grow arm muscle.

To grow arm muscle, you need to perform resistance training which includes a variety of exercises to engage the different arm muscles. These include the biceps brachii, brachialis, brachioradialis, and triceps. Additionally, a minimum of 10% surplus calories needs to be maintained, as well as a high protein diet.

Just over two years ago, I too was a skinny guy (I weighed a mere 130 pounds!).

These days, I’m weighing in at around 165 pounds at 12% body fat. And my arms look bigger than ever. In fact, my arm diameter has increased by over 2.5 inches!

In this post, I will be exploring the mistakes I made, which you should avoid (if you want to grow your arms).

So let’s go!

my personal experience of how to grow arms muscle
If I can do it you can too!
How to Get Bigger Arms For Skinny Guys! (BUILD MUSCLE FAST!)

Mistake #1: Not Learning About Basic Arm Muscle Anatomy!

The arm is composed of multiple muscles. Train all the arm muscles for maximum growth!

Most people know that the arms consist of the biceps and triceps. but did you know that there are way more muscles than that?

In fact, the upper arm contains 4 muscles, and these are further composed of even smaller muscles.(1)

Furthermore, the shoulders and forearm muscles attach to the upper arm. And growing these muscles will also contribute to a more aesthetically pleasing arm physique.

Here are the muscles you need to be training as a skinny dude trying to grow your arm muscles!

1. The Biceps Arm Muscle

Everyone knows the biceps. It is one of the most famous muscles out there!

But the bicep “bulge” is actually composed of 2 major muscles- the biceps brachii and the brachialis.(2)

The biceps brachii itself consists of a long head and a short head. Combined, these form the main peak of your bicep bulge.

The brachialis lies beneath the biceps brachii.

Although it may not be as visible as the biceps brachii, it’s the major driver of arm flexion! A larger brachialis muscle will also help fill out your overall bicep volume.

For more bicep information, check my guide on how to build bigger biceps.

2. The Tricep Arm Muscle

3 smaller muscles make up the larger tricep muscle- the medial head, lateral head, and long head.(3)

All three heads basically come together to form what most people call the triceps.

Additionally, the triceps make up approximately two-thirds of the muscle mass in the upper arm.(4)

So make sure you give your triceps some attention if you want to grow your arm muscles!

3. The Deltoids Shoulder Muscle

3 main muscles make up the deltoid- the anterior deltoids (front shoulder), lateral deltoids (side), and posterior deltoids (rear).(5)

The deltoids are technically classified as shoulder muscles. That being said, larger deltoids will help to give the visual impression of larger arms.

And this is particularly true for the anterior and lateral deltoids, which insert into the upper arm.

Therefore, working your shoulder muscles will also help to make your arm muscles look bigger!

Mistake #2: Not Applying The Correct Resistance Training Methods To Grow Arm Muscles!

optimise your training volume when considering how to grow arm muscle

When I first began working out, my sole mission was to get bigger arms. I was ready. My mind was pumped. I did my 100 bicep curls every week!

Nevertheless, my attempts were futile. My arms just would not grow. They remained skinny

I now realise that it takes much more than bicep curls to grow arm muscles.

Here are my three favourite training methods to focus on to build your arm muscles.

1. Optimise Training Volume

Doing 100 bicep curls every week may sound like a lot of work. But in terms of building arm muscles, it really isn’t.

Instead, I recommend increasing the total training volume for ALL the muscles in the arm (especially those I described in the previous section).

Training volume refers to the total number of sets, reps, and weights lifted each week. And increasing training volume will increase muscle growth.

So to increase training volume for the arms, you could add additional sets to target the biceps, forearm, triceps, and shoulders.

So how do you optimise training volume?

Keep your reps to around 8-12 reps per set because this is the optimal rep range for muscle growth.(6)

Then choose a weight-load which challenges you for those 8-12 reps. If your arm muscles aren’t fatigued by the end of your sets, increase the weight!

Finally, perform around 12-20 sets per week for each muscle. If you are also performing compound exercises on the side (which I strongly recommend), you could drop down to as low as 6-8 sets per week for each muscle.

Top tip- split this workload over 3-5 workouts throughout the course of the week. This will allow the maximum muscle-building opportunity for the arms.

2. Lift Heavy On Compound Exercises

If you want to build arm muscle mass, then go heavy on the compound lifting exercises. These lifts will activate multiple muscles in a single movement.

Additionally, most of the upper body compound lifts will also activate the arm muscles (especially the triceps).

Therefore, I recommend lifting heavy (with low reps) on compound exercises, since heavy lifting promotes muscular hypertrophy (growth).(7)

3. Lift Light On Isolation Exercises

If you want to define your arm muscles, then incorporate isolation lifts into your training programme. These lifts will work single muscle groups in a single movement.

Isolation lifts are good for adding definition to specific muscles (such as the biceps, tripes, or deltoids), but not so good for adding significant muscle mass.

Many trainers advocate lifting lighter weights (with high repetitions) for isolation exercises such as the bicep curl. This results in a bigger muscle pump.(8)

Therefore, to get the biggest arms possible, combine heavy compound lifting with light isolated lifting.

I personally like to lift heavy with 6-8 reps on the compound exercises and lift light with 12-15 reps on the isolation exercises.

This allows me to receive all the benefits associated with both of these lifts. To put it simply, I can increase my arm muscle mass, as well as add definition.

Mistake #3: Not Utilising A Variety Of Resistance Training Equipment To Grow Arm Muscle

how to grow arm muscle- include free weights, machines, resistance bands, and bodyweight exericises

Don’t get me wrong, dumbbell curls are a great way to pump up your biceps. And dumbbell arm extensions are an equally great way to build bigger triceps.

But you should also include other types of equipment in your training programme.

This is because different types of equipment will provide different patterns of resistance to your arm muscles. And this will help turn those skinny arms into big arms.

Additionally, different equipment types can cater specifically to those who prefer working out at home. And many skinny dudes do prefer working out at home.

Let me explain more about the different resistance training equipment you can use.

1. Free Weights To Grow Arm Muscle

build the arms with free weights

Free weights are your classic dumbbells and barbells (kettlebells too).

They provide very little guidance in way of lifting them. In other words, your muscles are doing 100% of the work.

This makes them the ideal equipment to grow arm muscle mass since they will also challenge the stabiliser muscles in your arms.(9)

The stabilisers are a group of muscles which function to hold your joints and body in place whilst you perform a lift. And training your stabilisers is a great way to help increase arm muscle, because it allows you to lift heavier!(10)

Additionally, free weights allow for greater freedom of movement. And this will allow you to target all your arm muscles by incorporating different lifting angles.(11)

So free weights are great. But as a skinny newbie who is interested in free weights, I would recommend starting with lighter weights first.


As a skinny beginner, your arm muscles may naturally be weak. Furthermore, the stabilisers may not yet be developed.

Therefore, lifting light will ease your body into things whilst reducing the risk of injury to the arm.

Additionally, choosing a lighter weight will also allow you to concentrate on form. And if there’s anything more important than growing big arms, it’s maintaining good lifting form.

Alternatively, you can start with weight machines before moving on to free weights. This will build up your overall arm strength, in preparation for the free weights.

2. Weight Machines To Grow Arm Muscle

build the arms with machines

Weight machines are all those crazy contraptions you see at the local gym. They are all essentially cables and handles attached to a weight stack.

Examples include bicep curl machines and tricep extension machines.

Why should you choose to use weight machines to grow your arm muscles?

Well, that’s because weight machines are guided exercises. This means the machine restricts the direction of movement, unlike free weights.

The guided nature of weight machines makes them great for skinny guys who have just begun their weight training since a limited range of movement also reduces the risk of joint injury.12)

Additionally, weight machines utilise a cable system. And this provides consistent tension on your arm muscles as they go through a lift.(13)

In contrast, free weights will often provide decreased resistance as you go through the lift.

Take the dumbbell bicep curl as an example- as your forearm approaches the shoulder, you will notice that the resistance decreases. In other words, the bicep curl becomes easier towards the end.

This is because gravity is no longer acting on the weight to challenge the bicep.

The consistent resistance provided by weight machines makes them a great way to stimulate hypertrophy.

For best results, I like to combine weight machine exercises with free weights to really grow my arm muscles.

3. Resistance Bands To Grow Arm Muscle

build the arms with resistance bands

These are basically giant elastic bands.

Resistance bands are cheap, safe, and extremely convenient to use (for beginners and experts alike).

But don’t let the simple nature of the resistance band fool you!

Resistance bands are an excellent way for skinny dudes to build arm strength and grow arm muscles(14).

I loved using them to maintain my arm muscles during the recent pandemic lockdowns.

Similarly to weight machines, they provide tension throughout the lifting motion. In fact, they provide even INCREASING tension as the band stretches.

The unique resistance profile of bands makes them an amazing way to add a new challenge to your arm muscles.(15)

If you are a skinny dude looking to grow arm muscles with resistance bands, I would recommend time under tension training (TUT).

TUT involves slow and controlled movements.

As a rule of thumb for TUT, I count for 6 seconds during the upward phase and then 6 seconds for the downward phase.

In the example of a resistance band tricep extension- extend the forearm for 6 seconds, then flex the forearm back for another 6 seconds.

This is a great way to grow arm muscles at home!

4. Bodyweight Exercises To Grow Arm Muscle

build the arms with body weight exercises

Did you know that your own body weight can often be the best way to grow your arm muscles?

In fact, it’s one of my personal favourites.

Bodyweight exercises are often also compound exercises by nature. And this makes them great to build bigger arms.(16)

Examples include the diamond push-up (for bigger triceps) and chin-up (for bigger biceps).

As an ex-skinny dude myself, I know that a lot of other skinny dudes prefer to begin their journey for bigger muscles, at home.

I get this. When I was a skinny dude 3 years ago, I hated going to the gym (everyone was always much bigger than me!).

Well, guess what?

Bodyweight exercises are a great way to grow your arm muscles in the comfort of your own home (or garage)! Just buy a pull-up/dip station, and you are good to go!

Mistake #4: Not Including A Variety of Different Exercises To Grow Arm Muscle

include a variety of exercises to grow the arm muscles

In the previous section, I explained why you should use a variety of equipment to grow bigger arms.

In addition to this, you should also include a variety of arm exercises for maximum muscle growth.

By including a variety of exercises, you will be able to hit all the different arm muscles. And this will result in an overall bigger arm.

And let me tell you, hitting all the muscles in the arm is SO important for larger arms! Especially for skinny guys who lack any significant arm musculature.

Here are my favourite arm exercises. Combined, these exercises will ensure all your arm muscles are engaged for growth!

1. Bicep Curls (Biceps)

This is the staple classic to grow biceps.

Bicep curls can be performed with free weights, machines, and resistance bands.

They will target the biceps brachii as well as the brachialis.(17)

2. Reverse Bicep Curls (Biceps)

This is a great exercise to complement the conventional bicep curl.

The reverse bicep curl can also be performed using free weights, machines and resistance bands.

This exercise will shift focus onto the brachioradialis for a larger forearm.(18)

3.Chin Ups (Biceps)

The chin up is a great compound bodyweight exercise. You will need a pull-up bar to perform this exercise safely though.

If the chin-up is too challenging, assisted chin-up machines can be found in most gyms!

Compound pulling exercises such as the chin-up are a great way to work all the bicep muscles in the arm.(19)

4. Rows (Biceps)

The row is another great compound exercise to grow your biceps.

It can be performed with free weights, machines, or resistance bands.

The major difference between the chin up and row in terms of building arm muscle, is that the chin up provides a greater range of motion.

If you think about it, your arm is fully extended when you are hanging from the bar. In comparison, the arm has a degree of flexion in the starting row position.

This means the chin up will provide a more challenging stimulus for the bicep.

However, the row is an easier exercise for beginner skinny dudes!(20)

5. Tricep Extensions (Triceps)

The tricep extension is an isolation exercise which will sculpt definition into your triceps.

It can be performed with free weights, machines, and resistance bands.

I personally feel that the free weight variation is less beginner friendly, as it requires balance and coordination to lift a dumbbell awkwardly over the head.

If you are a beginner who is interested in tricep extensions, I would instead recommend doing them on a machine or with resistance bands first. Then you can move on to the free weights.

The tricep extension will target all three heads of the triceps!(21)

6. Skull Crushers (Triceps)

Skull crushers are a compound-type lift which is great for growing arm muscle mass.

They are also great for a skinny dude trying to simultaneously get a bigger chest.

It is most commonly performed using free weights, but you can also use resistance bands.

Skull crushers offer a completely different kind of resistance to the triceps. This is because they force your triceps to work isometrically, and this is a highly effective way to build bigger triceps.(22)

7. Tricep Dips (Triceps)

Tricep dips are a popular bodyweight compound lift to grow the triceps.

They are also a great workout for skinny dudes who want to build bigger arm muscles at home!

If you don’t have a dip station, you can always use a chair (or any stable elevated surface). Furthermore, you can add weights to make the dip even more challenging.

I personally love dips. They are convenient to perform, and they offer numerous options for progression (tie a 5 kg weight to your waist to really push the triceps!)

Tricep dips will engage all three heads of the triceps.(23)

8. Bench Presses (Triceps)

The bench press is an awesome compound exercise that should be in any skinny guys training programme. And there are many bench press variations, all of which will help you to grow your arms (and chest!).

All bench presses can be performed with free weights, machines, resistance bands, and bodyweight (the bodyweight equivalent of a bench press would be the pushup).

My favourite bench press to grow the arms is definitely the narrow-grip bench press (or narrow hand push up).

A narrower grip will focus the majority of the weight onto your triceps, rather than the chest.

Additionally, you can change to a hammer grip press with dumbbells to really hit the triceps!

Both the narrow-grip bench press and hammer grip dumbbell press will effectively engage the triceps.(24)(25)

9. Overhead Presses (Deltoids and Triceps)

The overhead press is similar to the bench press, but the arms move upwards (parallel to the torso). In comparison, the bench press moves the arms outward (perpendicular to the torso).

The upward movement of the overhead press makes it excellent for engaging the shoulders as well as the triceps.

This exercise can be performed with free weights, machines, resistance bands, and bodyweight (handstand press up).

I love this exercise! It’s a great way to build arm muscle and develop an overall more powerful upper body.

The overhead press will work the triceps, anterior deltoids, and lateral deltoids.(26)

10. High Pulls (Deltoids And Biceps)

High pulls are basically an upright row. They are also compound exercises, making them a great way to build your arm muscles.

This exercise can be performed using free weights, machines, and resistance bands.

High pulls aren’t my go-to exercise to build arm muscle. That being said, they are a great compound move for building the upper body in general.

This is because they will activate the biceps, forearm, deltoids, AND back muscles.(27)

11. Lateral Raise (Deltoids And Biceps)

Lateral raises are an isolation exercise which is an awesome way to add definition to your shoulders. This will help to also make your arms look bigger.

They can be performed with free weights, machines, and resistance bands.

Lateral raises are amazing because they primarily work the lateral deltoids. And since the lateral deltoids join onto the upper arm, they will help to make the arm look bigger overall!(28)

Mistake #5: Not Eating The Proper Foods!

diagram which shows you need to consume proper nutrition to grow the arm muscles

First of all, you need to be consuming enough calories every day if you want to grow any muscle.

Now, this can be difficult for skinny guys as we naturally eat less. Our stomachs are also smaller!

That being said, it’s not an impossible task.

My advice is to track your daily calorie intake and macronutrient intake. And this allows you to stay on track with your calorie targets.

1. Track Your Daily Calorie Intake

This is essential in your journey to build muscle. More specifically, you should be consuming a caloric surplus.

Did you know that your body doesn’t want you to build too much muscle?

Yes, that’s right.

That’s because muscle requires a lot of energy to maintain. Therefore the body only wants to build as much muscle as it requires. No more, no less.

So how do you force the body to begin building muscle?

Eat a caloric surplus!

You should be aiming for around 200 to 300 calories above your total daily energy expenditure (TDEE). To do this, you should track your daily calories. And this is called calorie counting.

If you want to find out more about determining your TDEE and calorie counting, you can read my guide on how to build muscle!

2. Consume Enough Macros

In addition to consuming a caloric surplus, you will also need to consume enough macronutrients:(29)

  • Protein – aim for 1.2g to 1.6g per pound of body weight. This will provide the raw materials to build arm muscle!
  • Carbohydrates – aim for 2.5g per pound of body weight. Furthermore, make sure they are complex carbs and not simple carbs (avoid consuming large amounts of sugar!). This will fuel your workouts as well as the muscle-building process afterwards.
  • Fats – aim for 0.4g per pound of body weight. This will help fuel your workouts as well as promote muscle-building hormone release (testosterone and human growth hormone).

Mistake #6: Not Giving Your Body Enough Rest To Build Muscle

rest sufficiently to grow the arm muscles

Undertraining is a common mistake people make when trying to build arm muscle. But over-training is also common.

There’s a fine line between over-training and under-training. And both mistakes are very easy to make!

Therefore you should remember to allow your body sufficient rest.

But why is resting important?

You can spend your whole life training, but the fact of the matter is this- if you don’t allow your muscles time to recuperate, they will not grow!

I found the trick to building arm muscle is to optimise your training volume as well as give your body enough time to rest.

Here are my 3 best tips to make sure you are giving your body the rest it requires to grow those arm muscles.

1. Allow Yourself 2 to 3 Minutes Rest Between Sets

I personally found that a 2 to 3-minute resting duration is optimal for muscle growth.

2 to 3 minutes allows your arm muscles to recover most of their energy before you hit them with another set.(30)

Any less than 2 minutes, you could be denying your muscles of valuable energy resupply. And this would mean you are limiting your muscle-gaining efforts since you won’t be able to push them as hard in the next set.

Therefore, optimise your training volume with sufficient rest in mind!

2. Allow Yourself 1 to 2 Days Rest Between Workouts

Allowing your arm muscles to rest between training days is equally important.

So why can’t you expect to train your arms 7 days a week and expect growth?

Because during an arm workout, you are essentially destroying some of the muscle fibres in the arms. The subsequent repair process is what leads to muscular hypertrophy.(31)

Therefore, by denying your muscles rest days, you are also denying them of the chance to rebuild themselves!

If you are a beginner lifter, I would suggest 2 days of rest between intense workouts. As your arm muscles adapt to your training, you can reduce to a 1 day’s rest.

You will know the right time to make the transition from a 2 to 1-day rest because your muscles will feel ready for another arm pump!

If the arms are still very sore after 1 day of rest, that’s your body’s way of telling you to give it another day off!

3. Get Your 8 Hours Sleep

Sleep is so, so, SO important.

Did you know that during deep sleep, protein synthesis ramps up?

Additionally, human growth hormone is released. And this positively influences the muscle-building process.(32)

Therefore, by hitting your 8 hours sleep per night quota, you are allowing your body the opportunity to grow arm muscles!


That’s today’s question answered!

How to grow arm muscle is an extremely common question, especially for skinny guys who do not have much meat on their arms.

Today, I have shared with you 6 mistakes which I made when I started out as a skinny novice. Better yet, I have advised you on what to do instead.

I have described the importance of understanding basic arm muscle anatomy, shared 3 of my favourite training methods, compared the different training equipment, shared my 14 favourite arm exercises, and explained the importance of nutrition and rest.

If you combine the right arm exercises with an optimised training program, nutrition, and rest, you WILL be able to grow those arms!

Are there any arm training mistakes you have made that you wouldn’t mind sharing?

Feel free to send me a message if you have any questions! You can find my details on the “contact us” page.

You may also be interested in the downloadable Kalibre Blueprint PDF which details exactly how I gained 40lbs of lean muscle (it’s 100% free!). It details the exact exercises and nutrition (with printable worksheets) I used to go from skinny to ripped!

Thanks for reading guys!

Peace Out,


(Biochemistry BSc, Biomedical Sciences MSc, Ex-Skinny Guy)


I'm Kal (B.S, M.S)- a health & fitness writer and owner of Kalibre Fitness. I love to nerd out on weight training and nutrition. My primary interests are in muscle hypertrophy mechanisms and strength development. You can connect with me in the "Contact Us" section below!

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