You’ve seen the photos. The lighting is perfect, the vacuum pose is locked in, and Chris Bumstead looks like a literal Greek god carved out of granite. But if you look at the comments on any of his training videos, there’s one question that never goes away: "How big are cbums arms really?" People want a number. They want to know if he’s hitting that mythical 20-inch mark or if it’s all just "smoke and mirrors" created by a tiny waist and massive delts.
Honestly, the answer is a lot more interesting than just a tape measurement.
In the world of Open Bodybuilding, where guys like Nick Walker or Big Ramy roam, arms are often treated like separate entities—huge, bulging hams that look like they were glued onto the torso. But Cbum is the king of Classic Physique. In this division, it’s not about having the biggest limbs in the room; it’s about how those limbs fit the "flow."
The Number Everyone Is Looking For
Let's get the "official" stats out of the way, even though "official" measurements in bodybuilding are famously slippery. During his peak competition prep for his final Olympia runs, Chris Bumstead's arms generally measure between 19.5 and 20.25 inches. Wait. That’s it?
To a regular person at a commercial gym, a 20-inch arm is gargantuan. It’s a thigh with a pulse. But in the context of elite bodybuilding, where some Open guys are pushing 23 or 24 inches, 20 inches sounds... almost human.
But here’s the thing: Cbum is 6'1". When you spread 20 inches of muscle over a long humerus (the upper arm bone), it looks very different than it does on a guy who is 5'5". Because Chris has longer limbs, he has to pack on significantly more actual muscle mass just to make his arms look "full."
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Why His Arms Look Bigger Than They Are
If you stood next to him at a meet-and-greet while he’s wearing a hoodie, his arms might not shock you. But the second he hits a front double bicep on stage, they look massive. Why?
It’s basically an optical illusion powered by biology.
Chris has a notoriously tiny waist—we’re talking 30 inches or less when he’s stage-lean. When you pair a 20-inch arm with a 30-inch waist and 240+ pounds of lean mass, the proportions make the arms look like they're 22 inches. It’s the "V-taper" effect on steroids (pun intended).
Also, his triceps are the real stars. While everyone looks at the bicep peak, the triceps make up about two-thirds of the upper arm’s mass. Chris has incredible lateral head development—that "horseshoe" look. When that tricep is fully flared, it creates a width that makes the arm look thick from the side, which is arguably more important for the Classic look than a big bicep "ball."
How Cbum Fixed His "Weak" Arms
Believe it or not, for years, Chris and his former coach (and brother-in-law) Iain Valliere considered his arms a weak point. Seriously. They felt his back and legs were so dominant that his arms were disappearing in certain poses.
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To fix this, Chris didn't just "curl more." He changed his entire philosophy. He started incorporating FST-7 (Fascia Stretch Training) under the guidance of Hany Rambod. This involves doing seven sets of an exercise at the end of a workout with very little rest to gorge the muscle with blood and stretch the fascia from the inside out.
He also stopped ego-lifting. You’ll rarely see Chris swinging 80-pound dumbbells for curls. Instead, he focuses on:
- The Mind-Muscle Connection: "Squeezing" the muscle at the top rather than just moving weight.
- Long-Head Tricep Work: Doing overhead extensions to target the part of the tricep that adds the most "hang" to the arm.
- Neutral Grip Work: Hammer curls to build the brachialis, which sits under the bicep and literally pushes it up, making the arm look wider.
The 2024 Transition and Retirement Factor
Now that Chris has officially retired from the Olympia stage after his sixth title, his "stats" are going to fluctuate. In his 2024 off-season, he was likely walking around at 260–270 lbs, and his arms probably pushed past that 20-inch mark significantly.
But being "big" and being "Classic" are two different things. In his own words, he often felt he had to hold back on certain body parts to stay within the weight limits of his division. Now that he's "retired" (and briefly dabbled in the Open division in Prague), he doesn't have those limits.
Can You Get Arms Like Cbum?
Probably not. And that's okay.
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Chris has elite insertions. Look at where his bicep ends and his elbow begins. There isn't a huge gap there. That "fullness" is largely genetic. If you have "short" bicep peaks, no amount of preacher curls will make them "long."
However, you can use his logic. He prioritizes volume and blood flow over raw weight for arms. He treats them like a finishing touch rather than a primary mover.
Actionable Advice for Your Own Arm Growth
If you want to maximize your own arm size based on the "Cbum Method," stop doing 3 sets of 10 and going home. Try this:
- Prioritize the Long Head: Add an overhead tricep movement (like cable or dumbbell overhead extensions) to every arm day. This is the "meat" of the arm.
- The Brachialis Secret: Don't skip hammer curls. Building that small muscle between the bicep and tricep is the fastest way to add "thickness" when looking at your arms from the front.
- Controlled Eccentrics: Don't let the weight drop. Chris is famous for his slow, controlled negatives. Take 2-3 seconds to lower the weight on every single rep.
- Frequency over Intensity: Since the arms are a smaller muscle group, they recover faster. Try hitting them 2-3 times a week with moderate volume rather than once a week with extreme intensity.
How big are cbums arms? Big enough to win six Sandow trophies. But more importantly, they are perfectly proportioned. Whether they are 19 inches or 21 inches on any given day matters less than the fact that they complete the most iconic physique of the modern era.
If you’re looking to track your own progress, stop just looking at the number on the tape. Take photos in the same lighting every month. Look for the "separation" between the deltoid and the tricep. That’s where real "size" shows up. Focus on the quality of the muscle, and the quantity will eventually follow.