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How do interior designers use ratios and proportions?

After architects design the structure of a building, developers will often hire interior designers to make the inside of the building look inviting to residents and visitors. Like architects and builders, interior designers work with plans that are drawn to scale, organizing inside spaces with furniture and decorative elements.

If you're wondering why even scale matters in interior design, think about this. What happens when the furniture seems too big for the room? It makes the room feel small and cluttered. On the other hand, if the furniture is too small, there will be empty, unused space, and the room may seem cold and uninviting.

Just how do interior designers use proportions to do their jobs? Use the slideshow below to imagine the process of an interior designer working on a new room. Work out the problem on each slide before clicking the button to check your answer.

Designing a Home

overhead view of room layout

Suppose your company has been employed to design the inside of a home for a client. Architects have begun work on the plans, and you ask to look over the plans to get an idea of how you would design the interior space. The architect tells you that you are working on a scale of 2.5 inches to one foot. What does that mean?

A scale of 2.5 inches to one foot means that the ratio of inches on the plan to actual feet of building is 2.5:1 or \(\small\mathsf{ \frac{2.5}{1} }\).

How Large is the Room?

blueprint

A week later, your company receives a copy of the final plans for the home, and you decide to start on the living room. On the house blueprint, the length of the room is 25 inches long and 20 inches wide. How long is the actual room in feet?

Length
Let x equal the length. \(\mathsf{ \frac{2.5}{1} = \frac{25}{x} }\)
Cross multiply. 25 = 2.5x
x = 10 feet
Width
Let y equal the width. \(\mathsf{ \frac{2.5}{1} = \frac{20}{y} }\)
Cross multiply. 20 = 2.5y
y = 8 feet

Changes Are Made

painting and measuring supplies

Halfway through the design job, you receive a new set of plans. Only a few things have changed about the internal structure of the house, but it looks like the scale has changed! Now the scale is three inches to one foot. If the living room is supposed to be 12 feet high, how many inches should be drawn on the plans to show this height?

Let x equal the height in inches. \(\mathsf{ \frac{3}{1} = \frac{x}{12} }\)
Cross multiply. x = 36

The height drawn needs to be 36 inches.