Balls: size, volume and the lower one

Doctors measure testicles in millilitres, not inches. What the numbers mean, why one always hangs lower and how Greek sculptors got it backwards

Nobody measures balls with a ruler. Doctors measure them in millilitres, by holding each one next to a string of numbered beads and picking the bead that matches. That makes balls the only part of the male kit that is routinely graded like a wine glass, and the numbers are more interesting than you might think.

They also come with a built-in asymmetry that almost every man has, that most never notice, and that the ancient Greeks got half right and half wrong. More on that below.

How big, in millilitres

The tool is called an orchidometer: a row of wooden or plastic ovals, from 1 to 25 ml, threaded on a cord. The doctor feels the testicle through the skin and compares. It takes seconds, and it is what most of the reference numbers are based on.

Textbooks usually describe a normal adult testicle as somewhere around 15 to 25 ml. An Italian study gives a sharper picture: among white European men, the median was 22.5 ml in fertile men and 15 ml in men being seen for infertility. Both are healthy-looking numbers on the bead string, but they are not the same thing, and that matters more than any aesthetic preference.

Norms also depend on who you measure and how. Ultrasound gives smaller figures than the beads, and a 2026 ultrasound study of Somali men found averages of about 10.6 ml on the right and 10.2 ml on the left. That does not mean Somali men have small balls; it means you cannot compare a number from one method and one population with a chart made for another.

Why size matters here

Unlike the cock, the balls have a job where size is a genuine clue. Much of a testicle is made of tubes that produce sperm, so more volume usually means more factory floor. In the Italian study, smaller volume went with lower testosterone, fewer sperm and poorer sperm movement among the infertile men, and volumes under 15 ml, and even more under 12 ml, flagged men likely to have a poor sperm count.

That is a fertility statement, not a sexiness one. Bigger balls do not make a bigger cock, more stamina or a better top. And for gay men specifically, there is simply no study of what anyone prefers. The popular wisdom on the subject comes from straight escort blogs, which is not where this site takes its data from.

Why one hangs lower

Look in a mirror and you will probably see it: one ball sits higher than the other. In most men it is the right one that is higher and the left one that hangs lower. The surprise is that the right one is also, on average, slightly bigger, not smaller. So the lower ball is not lower because it is heavier.

Why the body does it this way is still debated. The point for the rest of us is simpler: uneven is normal. Two perfectly matched balls hanging at the same height are the exception, and the height changes anyway with temperature, as the chapter on the scrotum explains.

What the Greek sculptors got wrong

In 1976 the psychologist Chris McManus had an unusual idea for a letter to Nature: check the balls on ancient statues. Greek and Roman sculptors, obsessed with anatomical accuracy, almost always put the right testicle higher, exactly as in real men. But they also made the lower, left one visibly bigger, which is the opposite of real life.

His explanation is lovely. The Greeks probably reasoned like engineers: if the left one hangs lower, it must be because it is heavier. So they carved what they believed rather than what they saw. The paper later earned McManus an Ig Nobel Prize, the award for research that first makes people laugh and then makes them think.

Bronzes have their own stories. The Riace Warrior A, one of the most admired male bodies of antiquity, has a left testicle hanging markedly low. Two doctors looking at it suggested it resembles a varicocele, a swelling of the veins around the testicle, which nine times out of ten occurs on the left. Whether the model had one or the sculptor just liked the look, nobody can tell.

When to check

Most of what you can feel in there is supposed to be there: the testicle itself, smooth and firm, and the softer coiled tube along its back, the epididymis. Get to know your own so that you notice change. See a doctor if you find a new hard lump on a testicle, if one side swells or grows, or if a dull heaviness does not go away. Sudden, severe pain in a ball is an emergency, not something to sleep on.