If you're curious about the pros and cons of having an 18 inch neck, then you're in the right place. This article explains how to get an 18 inch neck (if you want one) for bodybuilding purposes and also discusses the downsides of having an 18" neck (there are definitely a few).
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How big is an 18 inch neck?
So, just how big is an 18 inch neck? For anyone, an 18 inch neck is very big indeed. If you're a man with an 18" neck circumference, then your neck is around 3 inches bigger than average.
An 18 in neck will look large and imposing on just about anyone. But if your neck consists of more muscle mass than fat tissue, then your neck will look especially big.
One study of college athletes (and these people weren't skinny runners) found that males only had a 15.5 inch neck on average.  This just goes to show how huge an 18 inch neck really is. You certainly don't get an 18" neck without direct training in most cases.
How about an 18.5 inch neck?
An 18.5 inch neck is very big indeed—around 3.5 inches bigger than normal, to be precise. But as you'll see later on, having an 18.5 inch neck isn't necessarily a good thing if you want to enjoy your best health.
From an aesthetic standpoint, however, having a lean 18 inch neck can make your physique look more powerful and imposing, which are two attributes that many men want to improve.
Having a thick 18.5 inch neck is an indication of having a strong neck,  something that can help to protect you from injuries during contact sports. Indeed, many combat athletes and football players have big necks because they need to protect themselves against concussions.
What shirt size is an 18 inch neck?
So, what shirt size should you get if you have an 18 inch neck circumference? In most cases, an 18 inch neck will be equal to a size XXL (that's two XL). If the rest of your body isn't as big (relatively speaking) as your neck, then you might need to get a custom-fit shirt.
Also, bear in mind that you want a collar with some breathing room. So if your neck measures 18 inches—and you want to be able to fasten your top button—then you need to get a collar that is at least 18.5 inches.
Who has an 18 inch neck?
Here are two real-life case studies of people with 18" necks so that you can see what an 18 inch neck actually looks like.
When you think of neck training, you probably also think of AlphaDestiny. Few people have done more in the online fitness world to promote neck training than Alex from AlphaDestiny.
Crucially, Alex has the neck size and training experience to back up his advice. His channel is a treasure trove of neck training tips that any serious natural lifter should explore.
Now, in terms of size, Alex's neck may well be bigger than 18 inches. I think he built it up to 19 inches at one point, scaled back his training for a while, and lost a bit of size. Maybe he's gained it back now. Muscle memory most definitely applies to the neck.
The man behind the YouTube channel W16 Fitness says that he's always had a big neck—when he started lifting, his neck already measured 18 inches.
He posted a video of himself doing neck curls with 55 lbs for two reps. It seems like he could've done way more reps, but since he does neck curls to improve his posture—and because he's already got a massive neck—there's little point in doing high volume training since it would just lead to unnecessary growth.
Watch until the end of the video to see what an 18 inch neck actually looks like on a natural lifter.
How to get an 18 inch neck naturally
Here's how to get an 18 inch neck naturally, even if you currently have a pencil neck.
Focus on the sternocleidomastoid
The sternocleidomastoid makes up the bulk of your neck size from the front and is best trained with neck curls (also called neck flexions), and side neck raises. You can use either a harness or regular weight places, depending on your preference.
While you shouldn't do max rep lifting on neck exercises, you also need to understand the importance of progressive overload when it comes to getting an 18 inch neck. Remember, an 18 in neck is big—you don't get a neck that size by just doing pump work (unless you're genetically blessed).
Try to increase the resistance on a monthly basis at least. It should be easy to gain strength initially because your neck will grow rapidly once you start training it for the first time (or if you start training it again after taking time off).
Of course, you should do neck extensions as well if you want to maximize your circumference gains. Still, the sternocleidomastoid is what gives your neck that thick meaty look from the front, so it's by far the most important neck muscle for aesthetics (and for posture improvement).
Increase the resistance regularly
As noted, you need to increase the resistance on a regular basis if you want to get an 18 inch neck. All else being equal, a stronger muscle is usually a bigger muscle. This definitely applies to the neck.
While you can definitely get a muscular neck with relatively light weights, building a truly huge 18" neck for most lifters means getting stronger over time. Ideally, you want to add weight while sticking to your high rep sets so that you can progressively increase your training volume and not just the raw weight on your forehead or neck harness.
Also, consider this: If you were trying to build arms of an equivalent size, would you just do high rep curls and pushdowns with the same weight? I doubt it. You'd try to gain strength regularly.
Do the same for your neck, and the results will come. While it's definitely a unique muscle, the neck responds to tension just like your other body parts. So once you've perfected your form, don't be shy to add resistance if your goal is to build an 18 in neck.
Maintain a higher body fat level
Your body measurements are always bigger when you're bulking, and the neck is no exception. While you might not have ripped abs while hanging around at 15-20% body fat, this hardly matters when you're trying to build a thick, meaty—and potentially intimidating—neck.
Now, I'm not saying that you should get fat. After all, as you'll learn in a moment, having a thick neck will likely increase your risk of having sleep apnea.
Nevertheless, maintaining a higher body fat level is one of the easiest and most underrated methods for looking big since all of your circumference measurements will have more padding around them.
Add in the fact that you'll be training your neck while eating in a surplus, and you have a mass-building double whammy that virtually guarantees you new neck growth.
Are there any downsides to having an 18" neck?
While there are definitely people in good health with an 18 inch neck (just look at the case studies), there's no denying that neck circumference is a risk factor for sleep apnea. 
Most medical professionals talk about excessive neck size in relation to neck fat. But since many large strength athletes (many of whom usually have big necks) often suffer from sleep apnea, it seems plausible that having an excessively muscular neck could also negatively affect your health.
If you have other risk factors, like obesity, a tendency to snore, and a large tongue or tonsils, then you very likely want to hold back on your neck training or even skip it altogether.
But don't fret; you can still look buff while having a neck that measures considerably less than 18 inches. On the other hand, many natural lifters who look after their health have been able to build an 18" neck with no side effects besides a bit of muscle soreness.
Conclusion: Should you build an 18 in neck?
There's no doubt that having an 18 inch neck will give you a more formidable and powerful physique—one that demands respect in and out of the gym.
But do you really need to build an 18" neck?
You can definitely have a big neck without it measuring 18 inches. This is especially true if you're relatively lean and have a proportional physique.
So what I'd say is this. Train your neck by all means, but go slow and steady at first and assess how you feel at various points so that you can decide whether to continue with your neck-building regime or just maintain what you've got.
- Esopenko, C., de Souza, N., Conway, F., Todaro, S. M., Brostrand, K., Womack, J., Monaco, R., & Buckman, J. F. (2020). Bigger Necks Are Not Enough: An Examination of Neck Circumference in Incoming College Athletes. The journal of primary prevention, 41(5), 421–429. https://doi.org/10.1007/s10935-020-00600-5
- TIERNEY, RYAN T.1; SITLER, MICHAEL R.1; SWANIK, C BUZ1; SWANIK, KATHLEEN A.1; HIGGINS, MICHAEL2; TORG, JOSEPH3 Gender Differences in Head–Neck Segment Dynamic Stabilization during Head Acceleration, Medicine & Science in Sports & Exercise: February 2005 - Volume 37 - Issue 2 - p 272-279 doi: 10.1249/01.MSS.0000152734.47516.AA
- Mayo Clinic. (2020, July 28). Sleep apnea - Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/sleep-apnea/symptoms-causes/syc-20377631