Cylinders
What you'll learn
A cylinder is a circle stacked into a height — so its volume is the circle's area times the height.
A cylinder is a prism with a circular base. Once you see that, its volume formula is no surprise at all.
A circle, stacked
The base is a circle, and the area of a circle is π r². Stack that to the height and you get:
V = π r² h
A cylinder with radius 2 and height 5: π × 2² × 5 = π × 20 ≈ 62.8 cubic units.
Loading 3D viewer…
Same rule, round base
It's the exact same idea as the box — base area times height — just with a round base instead of a rectangular one. Every prism, straight-sided or round, follows the same rule.
Check your understanding
Question 1 of 2
A cylinder has radius 3 and height 2. What is its volume?