If you’re buying a new TV then size is likely to play a crucial role in the decision-making process. However, when deciding how well a TV will fit in a room, people often confuse the size of the TV d by the company with the actual size of the TV. Here's a handy guide to make sure you don’t make the same mistake.
When buying a new TV, manufacturers are always quick to point out the screen size is x but that doesn't tell you everything. What the TV manufacturers are actually referring to is the diagonal measurement of the TV. In other words, the width of the TV when measured from the top-left corner to the bottom-right corner or vice versa. While that’s all well and good for deciding between a 55-inch and 60-inch TV, neither size refers to the actual width of the TV. Considering the TV is going to fit in a space that’s determined by the actual width, it’s good to understand how to calculate the actual width when you need to.
Pythagoras from math class? If you do then this should be a breeze. After all, TV-makers are telling you the diagonal of a triangle and that’s usually what Pythagorean theorem looks to calculate. In times where you have the diagonal already, then figuring out the width (or the height) requires reversing the formula. As a refresher, Pythagorean theorem is a2 + b2 = c2. In this instance, we know C as that’s the diagonal and while you’d normally need to know either A or B to calculate the other, aspect ratios are here to fill in the gaps.
How To Calculate TV Width Based On The Diagonal
For the last decade, most TVs sold feature a 16:9 aspect ratio. This effectively means for every 16 inches in width, there’s 9 inches in height. This formula therefore works for any TV that uses a 16:9 aspect ratio. If you’re considering a TV with a less than usual aspect ratio, then as long as you know the ratio, the same method can be applied. Using Pythagorean theorem, the diagonal squared is equal to the height squared + the width squared. With the aspect ratio used as these values then its 16 squared (256) + 9 squared (81) which equals 337. As 16 in the aspect ratio is the width, you divide 16 by the square root of 337 to end up with 0.87 (when rounded). Now to calculate the width of a TV you simply multiply the diagonal by 0.87. If all that sounds too confusing then here's the shortcut: If the aspect ratio is 16:9 then the rest of the math doesn’t matter as much as you can just multiply the diagonal by 0.87 to get a fairly accurate TV width measurement. For example, to calculate the width of a 50-inch diagonal TV then multiple 50 by 0.87 to end up with 43.5 inches - the width of the TV.
Here’s some other common TV sizes and their widths based on the formula: 32-inch TV (32 x 0.87) = 27.8 inches in width, 40-inch TV (40 x 0.87) = 34.8 inches in width, 50-inch TV (50 x 0.87) = 43.5 inches in width, 60-inch TV (60 x 0.87) = 52.2 inches in width, 70-inch TV (70 x 0.87) = 60.9 inches in width, 80-inch TV (80 x 0.87) = 69.6 inches in width
While this formula is pretty accurate for almost any 16:9 aspect ratio TV (give or take a decimal or two), you should the calculations are only for the width of the screen. Depending on the make and model, bezels come into play and their widths also need to be added to get the true width of the TV. Although, with many new TVs coming with incredibly small bezels, that’s less of a problem these days.