Volume of a solid
The volume of a solid is the amount of space it takes up. We can measure it by counting how many unit cubes fit inside. Each unit cube has every edge 1 cm and a volume of 1 cm³.
Key idea
Volume = number of unit cubes. Count the cubes in one layer, then multiply by the number of layers. Volume is written in cm³ (cubic centimetre).
Counting layer by layer
A neat way to count is to work out one layer first, then multiply by how many layers are stacked on top. This is faster than counting every cube one by one, and it helps you remember the hidden cubes at the back and bottom.
Worked example
A box is 4 cubes long and 2 cubes wide in each layer, and it has 2 layers. What is its volume?
One layer = 4 × 2 = 8 cubes. Two layers = 8 × 2 = 16 cubes. Volume = 16 cm³.
Remember
- One unit cube = 1 cm³.
- Count all the cubes, including hidden ones.
- Volume uses cm³, not cm or cm².