How Long Does it Take to Gain 20 Pounds of Muscle?

2026 Update: I’m not sure, but I think Jeremy Ethier may have called me out. In his latest video, currently at 1.7 million views, he claims that anyone saying it’s possible to gain 20 pounds of muscle in 3 months is being dishonest. If you google that claim, you’ll see my progress photos, some of my client’s progress photos, an AI summary that quotes me, and this article.

I see where the mistake comes from. It’s common mistake. What’s strange is that Jeremy Ethier disproves himself in his own video. I’ll go through it.

Gaining 20 pounds of muscle is a common goal for skinny beginners. If you’re starting off underweight, like I did, that will almost certainly be enough to bump you up to a healthy bodyweight. It’s enough muscle to look noticeably bigger and stronger, too. You’ll start picking up compliments from your friends and family members. It’s a big change.

Most skinny guys can gain 20 pounds within a few months. That’s long enough to build good habits and get some momentum going, but not so long that that it’s hard to keep up your motivation.

I’ve been helping skinny guys bulk up for 15 years. I’ll show you a ton of examples. You’ll see what it looks like on different guys, how lean their gains are, and how long it took them.

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Illustration of a skinny hardgainer with an ectomorph body type.

How to Know If You’re an Ectomorph

Most of us ectomorphs describe ourselves as being naturally skinny and we tend to have a hard time gaining weight. More specifically, though, ectomorphs are usually defined by having narrower shoulders, lankier longer limbs, thinner bones, and a lower body-fat percentage. Being an ectomorph is also associated with having a higher metabolism and a smaller stomach.

If you’re curious about whether you’re an ectomorph or not, there are a few simple tests that you can do. All you need to do is measure the width of your frame, the thickness of your wrists, and the length of your muscle bellies. You can do it at home in just a couple of minutes.

We’ll also cover how the various ectomorph traits affect our ability to build muscle, what our genetic muscular potential is, and how we should approach bulking up.

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