Volume of step prisms made simple
21 October 2026
Understanding step prisms
A step prism is a 3D shape made up of two or more rectangular blocks joined together at different heights, creating a 'step' appearance. These shapes often appear in 11+ maths questions.
How to find the volume
To calculate the volume of a step prism, break it down into separate rectangular blocks. Find the volume of each block, then add them together for the total volume.
Worked example
Imagine a step prism made from two blocks:
Block 1: 5 cm long, 4 cm wide, 3 cm high
Block 2: 5 cm long, 4 cm wide, 2 cm high (sits on top of part of Block 1)
First, find the volume of Block 1: 5 × 4 × 3 = 60 cm³
Next, find the volume of Block 2: 5 × 4 × 2 = 40 cm³
If Block 2 sits entirely on top of Block 1, add both volumes: 60 + 40 = 100 cm³
The total volume of the step prism is 100 cm³.
Supporting your child
Encourage your child to sketch the shape and label each block. Breaking a step prism into smaller parts makes finding the volume much easier and helps avoid mistakes.
Key insight: Breaking a step prism into simple blocks makes volume calculations clear and manageable for 11+ learners.
