How to Measure a TV and Work Out What Will Fit

A TV is measured diagonally across the screen, from one corner of the visible picture to the opposite corner, in inches. The frame around the screen and the stand are not included. To know whether a set will actually fit, you also need its width and height, which for a standard widescreen TV are roughly 87 per cent and 49 per cent of the diagonal.

How to measure the screen size

1. Switch the TV off so you can see where the picture area ends.
2. Hook a tape measure on the bottom-left corner of the visible screen, not the plastic or metal frame.
3. Stretch it to the top-right corner and read the length. That figure, in inches, is the screen size.
4. If your tape shows centimetres, divide by 2.54 to convert to inches.

Do not be surprised if the number is a fraction smaller than the size printed on the box. Many sets are sold by size class, and the visible diagonal can be slightly less than the rounded figure in the name.

Width and height from the diagonal

Almost all modern TVs use a 16:9 shape. Geometry turns the diagonal into the other two dimensions: width is about 0.872 times the diagonal and height about 0.490 times. The table below shows the screen area only; add the frame and, for height, the stand.

How wide is a 55 inch TV?

The screen itself is close to 48 inches (about 122 cm) wide. With a slim frame, the whole set usually comes out a little wider, so allow some extra room on each side and confirm the exact figure on the manufacturer's specification sheet.

How big is a 75 inch TV?

Its screen is roughly 65 inches wide and 37 inches tall, about 166 by 93 cm. That is wider than many standard media units, so measure the furniture before anything else.

Measure the space, not just the screen

A TV that matches the numbers on paper can still fail to fit. Check these points before buying or rearranging a room.

• Cabinet width and depth. Some stands are a single central pedestal; others are two feet near the edges, which need a surface almost as wide as the TV.
• Height under shelves. Add the stand height to the set's height and leave a gap for air to circulate.
• Wall mounting. Look up the set's VESA pattern, the spacing of the mounting holes in millimetres, and make sure your bracket matches it and is rated for the weight.
• Doors and stairs. A large boxed TV must fit through every doorway on the way in.
• Room for sound. If a soundbar will sit below the screen, check that it will not block the picture or the remote sensor. The guide on choosing a soundbar covers sizes and placement.

How far away should you sit?

There is no single right answer, but a widely used rule of thumb for 4K sets is to sit somewhere between one and one-and-a-half times the screen diagonal away. A 55-inch set, by that rule, suits a seat roughly 1.4 to 2.1 metres away. Older full HD sets usually look better from a little further back, because individual pixels become visible up close. The article on what 4K resolution means explains why pixel count changes the ideal distance.

Comfort matters as much as the maths. The centre of the screen should sit roughly at eye level when you are seated; a set mounted high above a fireplace often means tilting your head back for a whole film.

Common measuring mistakes

• Measuring the outside of the frame instead of the picture.
• Measuring width and calling it the screen size.
• Forgetting the stand when checking height under a shelf.
• Ignoring cable access at the back, which can push the set forward on a shallow unit.

Screens versus projectors

If the wall can take a bigger picture than any TV you would want to buy, a projector may be worth a look. Image size then depends on the distance between projector and wall, which the guide on setting up a projector at home walks through. Whatever you choose, a clean screen shows the picture properly; cleaning a TV screen without streaks takes a soft cloth and a few minutes.

Quick answers

Is TV size measured with or without the frame?

Without. Only the visible screen counts.

How do I measure a TV I have not bought yet?

Use the width and height from the table, then add the frame and stand dimensions listed in the product specifications. Marking the outline on the wall with painter's tape shows how it will look in the room.