A prism is a solid geometric figure with two identical ends and all flat sides. The prism is named after the shape of its base, so a prism with a triangular base is called a “triangular prism.” To find the volume of a prism, you just have to calculate the area of its base and multiply it by its height — calculating the area of the base can be the tricky part. Here’s how to calculate the volume of a variety of prisms. Volume and capacity are similar but here is how to calculate the volume of prisms.