Primary 5 · Measurement & Geometry

P5 volume of cube and cuboid

Volume is the space a solid takes up, counted in unit cubes. In P5, your child finds the volume of a cube or cuboid as length × breadth × height, and the volume of liquid in a tank, in litres.

Taught in: Term 2
Syllabus: 4 skills
Usual slip: Multiplying only two sides

Updated 10 October 2026

What your child learns in P5 volume of cube and cuboid

Four skills, each with what it looks like on a worksheet.

Follows the latest (2026) MOE syllabus

See the syllabus wording

building solids with unit cubes
measuring volume in cubic units, cm³/m³, excluding conversion between cm³ and m³
drawing cubes and cuboids on isometric grid
volume of a cube/cuboid
finding the volume of liquid in a rectangular tank
relationship between ℓ (or ml) with cm³

Build solids from unit cubes

Your child builds solids from unit cubes and counts them. Each cube is 1 cm³, so 12 cubes make 12 cm³. Big things, like a room, are measured in m³.

12 unit cubes

Draw cubes and cuboids on dot paper

On isometric dot paper the dots run in slanted rows. Your child joins the dots to draw a cube or a cuboid, with three faces showing.

Cube

Cuboid

Volume of a cube or cuboid

Volume = length × breadth × height, in cubic units. A cube uses the same side three times, so a 4 cm cube is 4 × 4 × 4 = 64 cm³.

Cuboid

Cube

Volume of liquid in a tank

The water in a tank is a cuboid too: length × breadth × the height of the water. Each 1 cm³ of water is 1 mℓ, so 1000 cm³ is 1 ℓ.

Water in a tank

Key facts and formulas

Term 2

Volume in unit cubesEach cube is 1 cm³. This block is 3 cubes long, 2 wide and 2 high. $3 \times 2 \times 2 =$ $12\,\text{cm}^{3}$
Volume of a cuboid $\text{length} \times \text{breadth} \times \text{height}$ Example $10 \times 6 \times 4 =$ $240\,\text{cm}^{3}$
Volume of a cube $\text{edge} \times \text{edge} \times \text{edge}$ Example $6 \times 6 \times 6 =$ $216\,\text{cm}^{3}$
Water in a tankVolume of water = length × breadth × height of the water $30 \times 20 \times 12 =$ $7200\,\text{cm}^{3}$
Water added or taken outVolume = length × breadth × the change in height $30 \times 20 \times 5 =$ $3000\,\text{cm}^{3}$
Litres and cm³ $1\,\ell = 1000\,\text{cm}^{3}$ 1 mℓ = 1 cm³Example $7200 \div 1000 =$ $7.2\,\ell$

Words to know

Volume: The space a solid takes up, counted in unit cubes.
Cubic centimetre: The volume of a cube with 1 cm edges, written cm³.
Three dimensions: Length, breadth and height. A solid has all three; a flat face has two.
Same unit first: Change every measurement to one unit, such as cm, before you multiply.

The sentence that costs the mark

A cuboid is 8 cm long, 5 cm broad and 3 cm tall. Find its volume.

The cuboid has three dimensions, not two.

What the working usually does

only8 × 5=40 cm²

Multiplies only the two sides of one face and stops. That gives the area of the face, in cm², not the volume of the box.

What the question asked

3 ×8 × 5=120 cm³

Multiplies the third dimension too, the 3 cm height. Three dimensions give a volume, in cm³.

Both are clean multiplications ending on a believable number, and 40 looks as reasonable as 120. The only tell is the mark on the unit: cm² is a flat area, cm³ is a solid volume, and only the third dimension makes it cm³.

The same P5 volume of cube and cuboid question, worked properly

Lah works through it the way she does every question in StudyLah: one step at a time, marking the picture as she goes.

A cuboid measures 8 cm by 3 cm by 5 cm. What is its volume?

Step 1 of 4▌

The volume of a cuboid is the area of its base times its height. Start from the three measurements on the drawing.
Find the area of the base first: 8 × 3 = 24 cm².
24 cm² is only the base. Multiply it by the height too: 24 × 5 = 120 cm³.
So the volume is 120 cm³.

Every question in StudyLah comes with a walkthrough like this one.

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Three quick P5 volume of cube and cuboid questions

Try them together, then tap to check.

Question 1

A cubical tank has sides of 20 cm. It is $\frac{3}{4}$ filled with water. Find the volume of water in the tank, in litres.

Show answer

Answer6 ℓ. The tank holds 20 × 20 × 20 = 8000 cm³, and $\frac{3}{4}$ of 8000 is 6000 cm³. 1 ℓ = 1000 cm³, so that is 6 ℓ.

Question 2

A tank 30 cm long, 10 cm broad and 8 cm high has water 5 cm deep. How much more water fills it to the brim?

Show answer

Answer900 cm³. The empty space above the water is 8 − 5 = 3 cm high, so it holds 30 × 10 × 3 = 900 cm³.

Question 3

The solid is made up of 1-cm cubes. What is the least number of 1-cm cubes that must be added to make it a cube?

Show answer

Answer17. The longest edge is 3 cubes, so the smallest cube is 3 × 3 × 3 = 27 cubes. The solid has 10, and 27 − 10 = 17.

Helping at home

How to tell it has clicked

You do not need to do the multiplication to check this. Look at the unit on the answer: a volume ends in cm³, with a small three. If it says cm², a dimension was missed.

Try this tonight

Fill a small box with sugar cubes or dice, one layer at a time. One layer is length × breadth, and the number of layers is the height. Ask your child to point at one layer, then at the whole box, and say which one the question is asking for.

Before and after P5 volume of cube and cuboid

Builds on
Primary 3 Length, Mass and Volume
Converts km, m, kg, g, ℓ and mℓ
Builds on
Primary 4 Area and Perimeter
Splits for area, traces for perimeter
Builds on
Primary 4 Nets
Unfolds the solids into nets
You are here
Primary 5 Volume of Cube and Cuboid
Builds cuboids from unit cubes
Leads to
Primary 6 Volume of Cube and Cuboid
Works backwards from a volume

In the PSLE's hardest questions

2025 Paper 1 Question 15: the painted block

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See how your child is doing on this topic

StudyLah marks each step separately, so you can see whether it was the setup or the arithmetic that cost the mark.

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