Welcome to our Surface Area of a Box page.

We explain how to find the surface area of a cuboid, or box, and provide a quick calculator to work it out for you, step-by-step.

Our calculator will find the surface area of both closed and open boxes.

There are also lots of worked examples and some worksheets for you to practice this skill.

Quicklinks to ...

This calculator finds the surface area of a cuboid (or box) when the side lengths are known.

- Choose the length, width and height of the rectangle: you can choose a whole number, decimal or fraction.
- You can type a fraction by typing the numerator then '/' then the denominator.
- You can type a mixed number by typing the whole-number part, then a space then the fraction part.
- Examples: 2 1/2 (two and one-half); 3 4/5 (three and four-fifths); 7 1/3 (seven and one-third).

- Choose your units of measurement (default is none)
- Choose your desired accuracy (default is 2 decimal places)
- Click the Find Surface Area button
- You will be shown the area as a decimal (and also a fraction if you typed the length as a fraction).

Below are the formulas for the surface area of both a closed box and an open box.

An open box is basically a normal box which does not have a lid so it is open at the top.

The formula for the surface area of a closed box (or cuboid) is: \[ A = 2lw + 2lh + 2wh \; \]

where l is the length, w is the width, and h is the height of the cuboid

The formula for the surface area of an open box (with no lid) is: \[ A = lw + 2lh + 2wh \; \]

A box, or cuboid, is a 3-dimensional shape made up of 6 faces, all of which are rectangles.

Each face of the box has an opposite identical face which we can see clearly if we look at the net.

So a box has 3 separate pairs of identical faces.

The surface area of the box is equal to the total of all the areas of the rectangular faces.

So the total surface area of the box is: \[ A = lw + lw + lh + lh + wh + wh = 2lw + 2lh + 2wh. \]

Find the surface area of the box below.

The box has the following dimensions:

- Length: 7 cm
- Width: 3 cm
- Height: 5 cm

The surface area of the box is:

\[ A = 2lw + 2lh + 2wh \; \]

where l is the length, w is the width, and h is the height of the box

So if we substitute the values of the length and width into this equation, we get: \[ A = 2 \cdot 7 \cdot 3 + 2 \cdot 7 \cdot 5 + 2 \cdot 3 \cdot 5 = 42 + 70 + 30 = 142 \]

The surface area of the box is 142 cm^{2}.

Find the surface area of the box below.

The box has the following dimensions:

- Length (l):12 in
- Width (w): 5 in
- Height (h): 3 in

The surface area of the box is:

\[ A = 2lw + 2lh + 2wh \; \]

So if we substitute the values of the length and width into this equation, we get: \[ A = 2 \cdot 12 \cdot 5 + 2 \cdot 12 \cdot 3 + 2 \cdot 5 \cdot 3 = 120 + 72 + 30 = 222 \]

The surface area of the box is 222 in^{2}.

Find the surface area of the box below, giving your answer to 1 decimal place.

The box has the following dimensions:

- Length (l): 5.6 cm
- Width (w): 4.3 cm
- Height (h): 2.5 cm

The surface area of the box is:

\[ A = 2lw + 2lh + 2wh \; \]

So if we substitute the values of the length and width into this equation, we get: \[ A = 2 \cdot 5.6 \cdot 4.3 + 2 \cdot 5.6 \cdot 2.5 + 2 \cdot 4.3 \cdot 2.5 = 48.16 + 28 + 21.5 = 97.66 \]

The surface area of the box is 97.7 cm^{2} to 1 decimal place.

Find the surface area of the open box below.

The box has the following dimensions:

- Length (l): 6 in
- Width (w): 3 ½ in
- Height (h): 2 ½ in

The formula for the surface area of an open box is:

\[ A = lw + 2lh + 2wh \; \]

So if we substitute the values of the length and width into this equation, we get: \[ A = 6 \cdot 3 {1 \over 2} + 2 \cdot 6 \cdot 2 {1 \over 2} + 2 \cdot 3 {1 \over 2} \cdot 2 {1 \over 2} = 21 + 30 + 17 {1 \over 2} = 68 {1 \over 2} \]

The surface area of the box is 68 ½ in^{2}.

We have created two worksheets for you to practice this skill.

The first sheet involves finding the surface area of different cuboids with simple numerical values for the side measurements.

The second sheet is the same as the first but has decimal and fractional values for the side measurements.

Take a look at some more of our worksheets similar to these.

We have a range of other area worksheets and support pages for a range of different 2d shapes.

We have a range of area and volume calculators to help you find the area and volumes of a range of different 2d and 3d shapes.

Each calculator page comes with worked examples, formulas and practice worksheets.

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Most of our calculators show you their working out so that you can see exactly what they have done to get the answer.

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