When does puberty start?

Last updated on August 6, 2022


Hello sir,

I have a question. Since I had my first ejaculation at 12-13, when did I start puberty?


The technical definition for puberty is the time when you begin to change from a child to an adult. Medically, this is defined as when your sex hormones (androgens for males) begin to rise in your blood. As these hormones rise, they trigger numerous changes in the body. The time that those changes take place is called “adolescence.”

The difficulty for you and me is that external changes are not seen for about a year after the hormones start to rise. Thus, the practical point of puberty is generally when the first external changes are noticed. For boys, this most often is a swelling of the scrotum. However, it is gradual enough that most boys don’t notice it. Usually, the first noticeable change is the growth of pubic hair or erections.

Even before you were born, your penis would stiffen. However, after puberty, your penis will swell and get longer, which is called an erection. Eventually, the glands inside your body mature enough to start producing semen, and this led to your first ejaculation. Since your first ejaculation came when you were about 12 or 13, I would guess that you started ejaculating early (in the middle of stage 2). That means your first external sign of puberty (the swelling of your scrotum) probably took place a year before and your hormones started rising about a year before that.


My first ejaculation came through masturbation just before my 13th birthday. Does this count as 13 years old or still 12 years old?

Also, I’ve been having nocturnal emissions since I was 13. Does this mean I started stage 4 early? My acne started around that time though I didn’t have a growth spurt at that time.


When we are dealing with timing, you have to remember that your body doesn’t keep track of your birthdays. A few days before your 13th birthday is close enough to just consider it as when you were 13.

The various systems of your body each mature in a set order, but between those systems, the order is not tightly coupled. One boy may be able to ejaculate when he reaches stage 2, but another boy may not start until he reaches stage 4. Acne generally gets bad during stage 4 but it can start earlier. This is why the calculator asks a large number of questions and then weighs the answers to give a guess as to how far you’ve progressed.

As I mentioned before, since you started ejaculating at 13, I am guessing that you are among the guys who started ejaculating in stage 2. That typically means you will start your growth spurt somewhere around age 14-15. Without additional indicators, I assume that your acne just came early.