Volume

Volume measures the space inside a 3D shape. It links closely to surface area and unit conversions, especially when working with cubic units.

Overview

Volume tells you how much space is inside a 3D shape.

It is measured in cubic units, such as \( \text{cm}^3 \), \( \text{m}^3 \) or \( \text{mm}^3 \).

\( \text{Volume} = \text{area of cross-section} \times \text{length} \)

In GCSE Maths, many volume questions are about choosing the correct formula, substituting values carefully, and remembering the correct units.

What you should understand after this topic

  • Understand what volume means
  • Choose the correct volume formula for each shape
  • Calculate volume of prisms and cylinders
  • Use formulas for cones, pyramids and spheres
  • Use cubic units correctly

Key Definitions

Volume

The amount of space inside a 3D shape.

Cubic Units

Units used for volume, such as \( \text{cm}^3 \) or \( \text{m}^3 \).

Prism

A 3D shape with the same cross-section all the way through.

Cross-section

The shape made by slicing through a solid.

Radius

The distance from the centre of a circle to its edge.

Height

The vertical distance from base to top.

Base Area

The area of the bottom face used in some volume formulas.

Capacity

A measure of how much a container can hold, often in litres or millilitres.

Key Rules

Volume measures space

Volume is the amount of space inside a three-dimensional object.

Use the correct formula

Each 3D shape has its own volume formula, so identify the shape first.

Multiply area by height for prisms

Volume of a prism = area of cross-section × length.

Always include cubic units

Write answers in units such as cm³, m³, or mm³.

Key Formulas

Cuboid

\( V = l \times w \times h \)

Cube

\( V = a^3 \)

Prism

\( V = \text{Area of cross-section} \times \text{length} \)

Cylinder

\( V = \pi r^2 h \)

Cone

\( V = \frac{1}{3} \pi r^2 h \)

Sphere

\( V = \frac{4}{3} \pi r^3 \)

Pyramid

\( V = \frac{1}{3} \times \text{Base Area} \times h \)

How to Solve

Step 1: Understand volume

Volume measures the space inside a 3D shape.

Volume is measured in cubic units.
Examples: \(\text{cm}^3\), \(\text{m}^3\).
3D shapes showing volume formulas including cuboid cylinder cone and sphere

Step 2: Identify the shape

Cuboid

Multiply 3 dimensions

Prism

Cross-section × length

Cylinder

Circle × height

Cone / Pyramid

Use \(\frac{1}{3}\)

Step 3: Key formulas

Cuboid: \( V = lwh \)
Prism: \( V = \text{area} \times \text{length} \)
Cylinder: \( V = \pi r^2h \)
Cone: \( V = \frac{1}{3}\pi r^2h \)
Pyramid: \( V = \frac{1}{3}\times \text{base area} \times h \)
Sphere: \( V = \frac{4}{3}\pi r^3 \)
Exam tip: Always write the formula first.

Step 4: Radius and height

Check radius vs diameter.
Diameter → divide by 2.
Use perpendicular height.

Step 5: Prisms

Same cross-section throughout.

\( V = \text{area of cross-section} \times \text{length} \)
Includes cuboids, cylinders and triangular prisms.

Step 6: Units

\(1\text{ cm}^3\)

1 mL

1000 cm³

1 litre

1 m³

1,000,000 cm³

Step 7: Exam method

  1. Identify the shape.
  2. Choose formula.
  3. Check measurements.
  4. Substitute values.
  5. Calculate.
  6. Write cubic units.

Example Questions

Edexcel

Exam-style questions focusing on volume of cuboids and cubes.

Edexcel

A cuboid has dimensions 6 cm, 4 cm and 3 cm.

6 cm 3 cm 4 cm

Find the volume of the cuboid.

Edexcel

A cube has side length 5 cm.

5 cm 5 cm 5 cm

Find the volume of the cube.

AQA

Exam-style questions focusing on prisms and cylinders.

AQA

A prism has cross-section area 15 cm² and length 11 cm.

15 cm² 11 cm

Find the volume of the prism.

AQA

A cylinder has radius 3 cm and height 8 cm.

3 cm 8 cm

Find the volume of the cylinder in terms of π.

OCR

Exam-style questions focusing on cones, spheres and formula-based solids.

OCR

A cone has radius 4 cm and height 9 cm.

9 cm 4 cm

Find the volume of the cone in terms of π.

OCR

A sphere has diameter 10 cm.

10 cm diameter = 10 cm

Find the volume of the sphere in terms of π.

OCR

A solid prism has cross-section area A and length l.

A l

Write the formula for the volume of a prism.

Exam Checklist

Step 1

Identify the 3D shape correctly.

Step 2

Choose the correct volume formula.

Step 3

Substitute values carefully, especially radius and height.

Step 4

Write the answer in cubic units.

Most common exam mistakes

Radius mistake

Using the diameter instead of halving it first.

Formula mistake

Using the cylinder formula for a cone, or forgetting the \( \frac{1}{3} \).

Units mistake

Writing \( \text{cm} \) or \( \text{cm}^2 \) instead of \( \text{cm}^3 \).

Shape mistake

Confusing surface area and volume.

Common Mistakes

These are common mistakes students make when calculating volume in GCSE Maths.

Using area units instead of cubic units

Incorrect

A student gives the answer in \(\text{cm}^2\) instead of \(\text{cm}^3\).

Correct

Volume is measured in cubic units, such as \(\text{cm}^3\) or \(\text{m}^3\). Always include the correct units.

Using diameter instead of radius

Incorrect

A student uses the full width in place of the radius.

Correct

If a diameter is given, divide by 2 to find the radius before using formulas involving \(\pi r^2\).

Forgetting the \(\frac{1}{3}\) factor

Incorrect

A student calculates volume of a cone or pyramid without dividing by 3.

Correct

The volume of cones and pyramids is \(\frac{1}{3} \times \text{base area} \times \text{height}\).

Confusing volume with surface area

Incorrect

A student uses surface area formulas instead of volume.

Correct

Volume measures the space inside a shape, while surface area measures the outside covering. Use the correct formula.

Incorrect rounding with \(\pi\)

Incorrect

A student rounds too early or inconsistently.

Correct

Keep \(\pi\) in your calculations until the final step, then round to the required accuracy.

Try It Yourself

Practise calculating the volume of 3D shapes.

Questions coming soon
Foundation

Foundation Practice

Calculate volume of cubes, cuboids and simple prisms.

Question 1

Find the volume of the cube.

4 cm

Games

Practise this topic with interactive games.

Games coming soon.

Frequently Asked Questions

What is volume?

The space inside a 3D shape.

What are common units?

Cubic units like cm³.

What is a common mistake?

Forgetting to cube units.