Rate My Ass

The AI starts with shape, because shape is what the rest of the read hangs on. It compares three widths, the waist, the widest point of the hips and glutes, and the upper thighs just below the glute fold, and notes how far down the widest point sits. That comparison alone separates the four standard shapes: round is fullest in the middle, square has nearly straight sides, heart flares from a narrow waist to its fullest point low down, and a V-shape is widest high and tapers towards the thighs.

Then it reads projection and lift. From a side-on photo that is how far your glutes sit behind the line of your lower back and thigh; from behind it is where the lower fold sits and how cleanly it separates from the thigh. It also separates what is frame from what is changeable. Pelvis width and hip dips are bone structure and do not train away; muscle and, to a lesser extent, where you carry fat are the parts that move.

Before any of that, it corrects for the photo. Arching the lower back adds a surprising amount of apparent projection, a camera held low enlarges everything below the waist while one pointed down over your shoulder shrinks it, and a phone held close distorts whatever is nearest the lens. The result names your shape, the detail that decided it, and one concrete training note for that shape, and it tells you when the pose or angle was doing the talking.

One photo from directly behind, from the shoulders to the knees, standing relaxed with your weight on both feet and your feet about hip-width apart. Wear as little as you are comfortable in: the less fabric, the more of the shape the tool can read, and anything baggy hides it. Hold the camera at hip height, or prop it up and use a timer, rather than shooting down over your shoulder, which shrinks everything below the waist. Stand naturally rather than arching your lower back or clenching, since both change the shape the photo shows. Even light from the front or side works best. For a read on projection, add a side-on photo taken the same way.

The four shapes are a fitness-community convention rather than an anatomical classification. They are useful because they point at real differences in where an outline is widest, but there is no measured threshold where a round shape becomes a heart, and plenty of people sit between two. When yours does, the tool names both.

A single photo also cannot separate muscle from fat with any confidence, so the tool says what your shape reads as rather than claiming to know what it is made of, and it never estimates body fat or weight. Pose and angle matter more here than for almost any other photo: an arched lower back, a low camera and a phone held close all add apparent size and lift, and the same person can read as a different shape in two photos taken a minute apart. Treat the result as an honest read of one photo, not a measurement of your body.

Online rating sites started with HotOrNot in 2000, and the glutes got their own corner of that world long before any AI was involved. What changed in the 2010s was the target. Fitness culture moved from chasing a flat, lean look to building shape, the barbell hip thrust went from an obscure accessory lift to a gym staple largely through the coach Bret Contreras, and glute training became a genre of its own. The cosmetic version grew alongside it: the Brazilian butt lift became one of the fastest-growing cosmetic surgeries of the decade, and a 2017 survey of plastic surgeons put its death rate somewhere between 1 in 2,000 and 1 in 6,000 procedures, then the highest of any cosmetic operation. That is the context for this tool never suggesting surgery or fillers. Everything it recommends is training.

The four glute shapes

The shapes are named by where the outline is widest, which is why the tool compares widths before it names anything.

The three glute muscles

What people call their glutes is three muscles, and they shape different parts of the outline.

Hip dips are bone, not a flaw

Hip dips are the inward curve on the side of the hips, between the hip bone and the top of the thigh. They come from the skeleton: how wide your pelvis is, and where the top of your thigh bone sits against it. Nearly everyone has them to some degree, and how visible they are depends mostly on that structure and on where you carry fat, not on how fit you are. Training the gluteus medius can soften them a little. Nothing removes them, and the tool will only mention them as part of your shape, never as something to fix.

What actually changes your glutes

Muscle is the part you control, and it responds to the same thing every muscle does: heavy enough work, done consistently, getting harder over time. In practice that means a hip-extension lift such as the hip thrust or Romanian deadlift, a deep squat or split squat, and some abduction work for the upper glutes, two or three times a week, with enough protein to build on. Visible change takes months rather than weeks. Fat distribution is largely genetic and shifts with age and hormones, which is why two people doing identical training can end up with different shapes, and why the tool reads your shape rather than grading it.