Every penis head is unique, but there are some common shapes. Many penises fit very well into a particular shape category, and others seem to be a mix of two of them.
The "Standard" penis head, which you can see below, is both curved and a bit pointed. This is the shape that most people think of when they imagine the head of a penis. The head is larger at the base than at the tip, and the underside of the head is curved smoothly.
The "Triangle" head is much more pointed than the standard one. Instead of a smooth curve from the base to the tip, it has more of a straight line edge. The underside is very much like the standard head shape.
The "Knob" head is very different from the standard and the triangle. It is like one big curve from the base all the way to the tip. The tip is not pointed at all, and is more like a doorknob. The underside of the knob head is round just like the top.
The "Helmet" head is like the standard, just with more extreme curves. The base curves more sharply on the way to the tip, almost going a bit inward before bending up to the tip. The tip is more rounded than the standard, and the underside of the head is more extremely curved.
The "Bullet" head is like a knob head that has been stretched. The tip is more pointed than a knob head, but it is still more round than the standard. The underside is often very smoothly round, as well, making the whole head look like a bullet.
No matter what head shape a penis has, it can have a variety of sizes. Check out the size models below. A small head is one that is not as wide as the shaft of the penis. A normal head is one that is roughly the same width as the shaft. It can be a bit wider than the shaft or a bit more narrow. Both size differences are common.
A large head is significantly wider than the shaft. It often looks like a bulb on top of a thick stem. A mushroom head extends much beyond the width of the shaft. It is called a mushroom head because...well...it looks just like a mushroom on a stem. No matter how thick the shaft of a penis may be, a mushroom head is always much wider.
Penises come in a wide range of lengths. At The Penis Museum, we categorize lengths according to the chart below. We do this because we must assign some category to everything in the museum so that it can be properly organized. The sizes are just a general guideline, of course. One person may consider a 7 inch penis quite long while another person may think it is not all that long, for example.
Just like penis length, we have a system of categorizing penis girth in the museum. The chart below shows the ranges and titles for those ranges. For both the penis length and girth, the "Average" categories represent roughly 50% of all penises.
Once we've categorized penis length and penis girth, we place the whole penis in a size category. The ranges for the categories are based upon the length and girth classifications. Note that there is a bit of room for variety within the size categories. In the chart, the first category of each listing is the length and the second category is the girth. There are more categories for larger penises because those length and girth categories are quite rare. Any combination of the larger measurements makes for a large size category.