Once upon a time, when the Golden Age of bodybuilding was still in its early days, Steve Reeves’ 18.5-inch arms were the pinnacle of aesthetics, size, and symmetry.
Two decades later, seven-time Mr. Olympia Arnold Schwarzenegger raised the bar even higher to an unbelievable (literally) 22 inches.
Today, the biggest biceps in bodybuilding history — an intimidating 24 inches around — belong to the modern phenom Roelly Winklaar.
But are 100% natural 20-inch arms really possible for the rest of us?
Learn more below!
Table of Contents
- The Average Arm Size In Men Is …
- Bodybuilders & Athletes With 20-Inch Arms
- Are Natural 20-Inch Arms Possible?
- The Truth About 20-Inch Upper Arms
The Average Arm Size In Men Is …
20-inch arms fit the definitions of humongous, ginormous, gigantic, monstrous, literally any word that means “f’in huge.”
But how do 20-inch biceps compare to the average guy? The table below describes the typical unflexed, unpumped upper arm circumferences for men by age group:
|Age Group||Arm Measurement (Inches)||Arm Measurement (Centimeters)|
|20–29 years old||13.27 inches||33.7 centimeters|
|30–39 years old||13.78 inches||35.0 centimeters|
|40–49 years old||13.90 inches||35.3 centimeters|
|50–59 years old||13.54 inches||34.4 centimeters|
|60–69 years old||13.39 inches||34.0 centimeters|
|70–79 years old||12.91 inches||32.8 centimeters|
|80+ years old||12.17 inches||30.9 centimeters|
If we assume that flexing adds an extra two inches (on the high end), the average male 20-something has 15.27-inch arms. Or, he’s 4.73 inches away from 20-inch beasts.
Does that sound realistic?
Bodybuilders & Athletes With 20-Inch Arms
We’re well aware that the phrase “natural bodybuilder” is somewhat of an oxymoron. (In 1989, 54% of bodybuilders in Kansas and Missouri admitted to using anabolic steroids.)
But, if you want to imagine what 20-inch bazookas truly look like, check out these examples. Again, this is purely for size comparison, and we can’t verify the “natural” part here!
Leroy Colbert entered the bodybuilding world in the early 1950s, clinching his first career title — Mr. New York City — at age 19 before rising to the ranks of Mr. Eastern America in 1953. Yet, his true claim to fame was becoming the first natural bodybuilder to sculpt 21-inch biceps.
Sergio Oliva dominated the bodybuilding scene in the late 1960s, becoming one of the few to defeat Arnold Schwarzenegger to take home his third consecutive Mr. Olympia title. The Cuban native stood at an intimidating 5’10” and 225 pounds with massive 20.5-inch arms at his sides.
Larry Scott (nicknamed “The Legend”) led a career of firsts. The 5’7”, the 207-pound athlete became the first-ever Mr. Olympia (1965) and the first professional bodybuilder to sculpt 20-inch biceps using Vince Gironda’s famed methods (i.e., preacher, spider, and standard curls).
Larry Wheels is a modern-day bodybuilder known for his career-best 610-pound bench press, 810-pound back squat, and 855-pound deadlift (2,275 total). His upper arms measure in at a startling 21 inches to complement his towering 6’1”, 244-pound physique.
Get the FREE Shredded Body Checklist!
The 4 Steps to Build Noticeable Muscle Definition (without Turning Your Life into a Dumpster Fire!)
By entering your email address you agree to receive emails from Noob Gains. We respect your privacy and you can unsubscribe at any time.
Are Natural 20-Inch Arms Possible?
The odds of sculpting 100% natural, lean 20-inch arms are undoubtedly slim for the average male. However, this goal isn’t necessarily impossible either, at least for a lucky few.
For the average person, 20-inch arms are genetically unrealistic. Yet, the likelihood of building 20-inch natural arms ultimately depends on several factors, like:
Strength coach Charles Poliquin trained over 800 Olympic athletes during his career and became a voice of reason in bodybuilding and fitness magazines (like T-Nation).
One piece of Poliquin’s advice is still parrotted by bodybuilders everywhere: gaining 10–15 pounds will add an inch to your biceps.
Any growth beyond the 18-inch mark could require 25 pounds gained per inch!
Bodybuilder and top-four Mr. Olympia contestant Lee Labrada agree with this theory, though he specifies it’s 10–15 pounds of muscle mass.
If we consider this the gold standard for upper arm potential, here’s how much weight you’d have to gain for 20-inch biceps:
|Current Biceps Size||Estimated Weight Gain for 20 Inches|
|14 inches||90–110 pounds|
|15 inches||80–95 pounds|
|16 inches||70–80 pounds|
|17 inches||60–65 pounds|
|18 inches||50 pounds|
|19 inches||25 pounds|
Remember that muscle growth requires weight gain.
Even if you can’t fathom packing 70–110 pounds onto your lanky frame, any extra poundage combined with some sort of resistance training will translate to thickened muscles.
Natural Bodybuilding Potential
The Charles Poliquin theory is a good rule of thumb for men pursuing smaller physique milestones (i.e., one inch of arm growth at a time instead of 20-inch arms).
However, the rule doesn’t take into account body type (ectomorph, mesomorph, endomorph), current arm circumference, diet, or genetic factors.
Strength Steve Shaw created his own Natural Bodybuilding Formula based on the research of Dr. Casey Butts to determine the lean mass potential by height and body fat percentage.
According to Shaw’s calculations, a 6’0” male will max out at ~189 pounds of non-fat mass (give or take). If he weighs 210 pounds with 10% body fat, he’s essentially at his natural lifetime peak.
If his biceps currently measure 17 inches, a 20-inch goal isn’t rooted in reality. Yet, if he’s 6’0”, 130 pounds with 15-inch arms, he could potentially gain 80 pounds of lean mass to hit that goal.
Body Fat Percentage
Arms that measure 20 inches around are one thing. 20-inch lean, defined biceps are a completely different beast.
Take strongman competitors Brian Shaw (25 inches), Eddie Hall (28 inches), and Zydrunas Savickas (22.8 inches). These men arguably have some of the largest arms in modern history.
While ridiculously strong and muscular — Shaw can squat 904 pounds and rack pull 1,365 — these world-class athletes also weigh 385, 362, and 375 pounds, respectively.
Reaching that incredibly rare 20-inch milestone often means being less picky about whether the growth comes from fat, muscle, or a combination of the two.
The 20–25% body fat percentage, while high, could add 1–2 inches to your upper arms. If you already have 18 or 19-inch biceps, simply gaining any weight can add those final inches.
Nobody packs on mass like a newbie with a brand-spankin’ new gym membership, the appetite of a lion, barrels of protein powder, and a disturbing amount of free time.
But natural, lean 20-inch biceps don’t sprout up overnight, and noob gains don’t last forever. The best way to maximize your arm size, even if they don’t reach 20 inches, is time.
Exercise physiologist Lyle McDonald theorized that lifters can gain 40–50 pounds of lean mass before maxing out their physiques in what he calls the Model for Genetic Muscular Potential:
|Years of Training||Lean Mass Gained Per Year|
2–3 pounds of lean mass gain per year sounds slow. But then again, bodybuilder Lou Ferrigno gained 48 pounds between his Hulk days in 1975 to his Mr. Olympia comeback 17 years later.
Back to the Poliquin rule, if McDonald’s formula also holds true, it’s possible to gain ~37–46 pounds of muscle in four years — or up to 4.6 inches around the biceps for an average arm.
Still, since growth drops in half each year and requires more mass after the 18-inch mark, the progress toward 20-inch arms will either be unbelievably slow or eventually plateau.
Men with the best odds of building natural 20-inch arms happen to have genetics on their side. Research into the muscle-wasting disease sarcopenia links 50–80% of lean mass to genetics.
But just how much a difference does your bloodline actually make in the gym?
According to one 2008 study, “a lot.” The study measured hypertrophy in the knee extensors after 16 weeks of resistance training.
By the end of the study, half of the participants increased muscle size by 28%. The remaining 50% of participants saw split results — half grew by 58%, and half showed no growth whatsoever.
Men who build mass quickly or with less effort are more likely to see 20-inch arms, though it’s still a rarity in natural athletes.
There’s no definitive link between wrist size and maximum upper arm size. Yet, if we’re strictly talking proportions and symmetry, the Steve Reeves “classic” physique is the best example.
In his book Building the Classic Physique (clever), Reeves reveals that an ultra-symmetrical arm measures 252% the size of the matching wrist.
For a 20-inch arm, that’s a ~7.94-inch wrist. (We’ll round that up to an even 8.) Men with 8-inch wrists fall into the 81st percentile, meaning just 19% of guys have wrists larger than that.
Steve Shaw’s general rule of them is to add about 10 inches to your wrist size to determine your maximum upper arm size (<15% body fat). That means you’d need tree-trunk 10-inch wrists.
Again, this is more aesthetic than scientific.
Height is one of those “does it or doesn’t it?” factors when it comes to deciding what influences potential arm size. Are taller bodybuilders more likely to have higher, wider, and fuller biceps?
While a 5’5” bodybuilder with 17-inch biceps will look bigger by comparison to a fellow competitor with longer arms (who’s, say, 6’2”), height has little to do with mass potential.
In fact, some of the shortest bodybuilders in history have arms thicker than 20 inches, like:
- James Lewis (5’5.5”): 22 inches
- Lee Priest (5’4”): 22 inches
- Franco Columbu (5’5”): 19 inches — close enough
- Shawn Ray (5’7”): 23 inches
Biceps with longer muscle bellies and shorter tendons (ideally <2 fingers between the forearm and edge of the flexed biceps) tend to support the more natural growth of the fibers.
20-inch boas still aren’t likely, but your odds are now slightly better.
Biceps & Triceps Size
A caloric surplus (15% above maintenance) and 0.5–0.8 grams of protein per pound of bodyweight will repair microtears, thicken muscle fibers, and build new ones.
If you’re not fueling your body for muscle protein synthesis and growth, natural 20-inch arms are not even remotely realistic.
But training the proper muscles is equally as important (duh, right).
Remember that the 20-inch number is also a flexed circumference at the peak of your biceps. In other words, the measurement will increase whether you add height, width, or both.
Progressing toward 20-inch upper arms — even if you ultimately fall short — requires larger:
- Biceps brachii
- Brachialis (under the biceps)
- Coracobrachialis (connects the scapula to the humerus)
- Triceps brachii
It’s also not possible without proper technique and knowledge of training principles.
Heavy sets, 6–12 reps per set, training at 65–85% of your 1RM, and 60-second rest periods between sets (for maximum growth hormone release) are most likely to trigger hypertrophy.
The Truth About 20-Inch Upper Arms
To be completely honest, unless you’re a “genetic freak” with naturally massive muscles, building 20-inch arms will be a steep uphill battle or even impossible for most men.
But what if you really want to brag about having 20-inch arms? Is there anything you can do to make that happen without … taking shortcuts?
Truthfully, no. But here’s what you need to know:
How to Measure Arms Properly
Before you wallow in the sadness of your s**tty genetics, make sure that you’re actually measuring your arms properly to get an accurate reading.
With a cloth measuring tape:
- Rest your elbow on a hard surface, like a table or countertop.
- Make a fist with the same hand.
- Bring your forearm toward your shoulder to about a 45-degree angle.
- Find the roundest part of your biceps.
- Wrap the tape measure flat around the upper arm.
- Record the number where the tape overlaps.
It doesn’t hurt to measure a second, third, or fourth time to get an average reading. (If your first measurement reads 14 inches and your next is 17 inches, get somebody else to help you.)
Measure Them Pumped
It’s an unspoken rule that body measurements only count if you measure the muscles cold — typically at least 12 hours after your last arm workout and once muscle swelling has gone down.
Yet, not everyone follows that rule. In fact, Schwarzenegger’s claim of having 22-inch arms wasn’t a cold measurement; it was “pumped” (and actually about two inches off — oops).
It’s extremely likely that other bodybuilders claiming to have 19, 20, or even 22-inch biceps are being slightly misleading and sharing their pumped measurements.
As long as you’re honest about the dumbbell curls and cable pushdowns that came before it, there’s no harm in measuring them pumped. It can also add 0.75–1.5 inches to your arm size.
Nobody Cares About the Exact Number
The thing about arm size is that, outside of the locker room at a bodybuilding competition, literally nobody cares about the exact measurement of your biceps.
There’s no instant respect from guys at the gym once they find out you crossed the line between 19 and 20 inches. Girls won’t gossip to their friends about your huge 20-inch anaconda.
If you ask this question on a site like Reddit, Quora, or Bodybuilding.com, most responses will be “bro, why do you care so much?” or “16 or 17-inch biceps are big enough!”
Seriously, 15, 16, and 17-inch biceps are already well-above-average and deserving of bragging rights. Some things just aren’t meant to be — like naturally built 20-inch arms.
Build a Superhero Body Without Training Like One
Getting in shape isn't easy. But this program gives you a real-life approach to building a leaner, more muscular body without obsessing over fitness 24/7.