Is there a simple way to find out the actual width of, say, a 40" television screen?

Only if you know one of the dimensions or the aspect ratio.

Tape measure should work.

Ours is 55” & simple tape measure does the job, diagonally, as you say.

@ragingloli He does. C squared equals 40.

@canidmajor
That would only work if a and b are equal.
If he knows the aspect ratio, 1:X, he can calculate it with a=√(c²-(Xa)²).

20” ish X 35” ish
Used Pythagoras.
And aspect ratio of 16:9

They can’t all be the same. I imagine it depends on each maker, each model etc.?

There tend to be stock sizes.

The last time I bought a TV, I had to go to the specs on the website for the TV where it gives you the exact width and height (with and without the stand). You’d think there would be an industry standard, but it depends on the make and model. At the time I bought mine, I had a specific location with a specific width and height so I had to be careful. I chose 3 different TVs that I liked but only one would fit in my available space, so that’s the one we purchased. Amazon carries most brands and models and they are very good at supplying the specs.Walmart is too. Even if you don’t buy from either of them, you can get the dims off their website. Or you can go to the specific brand and search the model number to get the same info.

Using graph paper, measure out a box in a 9X16 ratio using 1 box on the graph paper for each inch, transfer a diagonal line across the box. Measuring horizontally, mark a line that is 40” (squares) across and transfer that line to the diagonal. Then square off the box and note the measurements indicated by the diagram for both horizontal and vertical measurements. You may have to add 2 inches or so (top to bottom and left to right) to compensate for the edges of the screen.

The “measure diagonallly” is old school, for the old cathode ray tubes, that were in the 4:3 ratio aspect. Since the industry has switched almost completely to 16:9 flat screens, TV sizes are advertised in terms of width. If you go to Best Buy with a tape measure, you’ll see that a 32” screen is 32 inches across, with maybe a 3/8 inch frame around the whole screen.

The 40 inch screen I had up until last year was 40¾ wide, frame included.

My 40” was advertised at 39.5” diagonally. Screen width is 34¾”. My old 32” HDTV (screen) was 32” diagonally.

If the aspect ratio is 16:9, a 40” diagonal TV should be about 34.86” wide, and about 19.61” high.

16/9=1.7777
34.86/19.61=1.7777
34.86^2=1215.2196
19.61^2=384.5521
1215.2196+384.5521=1599.7717
√1599.7717=39.997
C^2=1600
√1600=40, which is the diagonal length.

I would use a tape measure.

I went to Amazon to look at what was available

TCL 40S325 40 Inch 1080p Smart LED Roku TV (2019)
35.6×7.2×22.7 in

TCL 43S425 43 Inch 4K Ultra HD Smart Roku LED TV (2018)
38.2×7.6×24.5 in

Samsung UN43RU7100FXZA Flat 43-Inch 4K UHD 7 Series Ultra HD Smart TV with HDR and Alexa Compatibility (2019 Model)
38.2×8.3 x 25.1 in

I realize that 2 of them are 43” but I only founf one 40” set available. Several companies are no longer offering the 40” opting to go to the 43”,

If I needed to know and was shopping online, I’d look up the dimensions in detailed specs for the model.

That’s the beauty about having the internet available, you can look up the specs without being obligated to buy it there

I only measure the actual screen diagonally.
With the frame it then looks like 40 inches but actually 38 inch screen.

Who’s the innumerate moderator who deleted my answer?

Is there a simple way to find out the actual width of, say, a 40” television screen?

Divide the diameter by 1.15

What is the width mean to begin with? Is it the shorter one?
http://www.differencebetween.net/science/mathematics-statistics/difference-between-length-and-width/

…“What does the width mean..”