How to work out the Diagonal screen size

The measurement of a LCD or projection screen size contains 3 critical measurements – Width, Height and Diagonal.

Depending on which part of the world you are based will determine how you measure a screen. You will exclusively use imperial (inches / feet) or metric AND imperial. If the latter you will always typically use metric for the Height and Width and Imperial for the diagonal.

So here is how to work out the diagonal if you know the width and height also based on mathematics you learnt at school but probably forgot known as Pythagorean Theorem.

Two adjacent sides of a rectangle, along with a diagonal, make up a right triangle. So to solve for the diagonal, use the Pythagorean Theorem:

Find the diagonal of TV format screen that 3m x 4m:
3m and 4m, the diagonal will be sqrt((3×3) + (4×4)) = 5m.
3×3 =
4×4 = 16
square root of 25
5×5 = 25
therefore the diagonal is 5m
1m = 39.37007874 inches

The same formula applies
4m 16:9 screen

2.28m H and 4m W, the diagonal will be sqrt((2.25×2.25) + (4×4)) = 4.5m (approx)
2.25m x 2.25m = 5.06m
4×4 = 16
5.06 +16=21.06 …now for strange numbers we need to guess and average
square root of 21.06
4.5 x 4.5m = 20.25 (or could have guessed at say 4.6m)
therefore the diagonal is 4.6m roughly
1m = 39.37007874 inches
181″ diagonal called
called 180″ diagonal screen
The exact diagonal is 4.589117562233506 m or 180.6″ dia

If you know the width of a screen everything else can be worked out…
5.5m wide screen 16:10
5.5 / 16 = 0.34
0.34 x 10 = 3.44m High
5.5mWm x 3.44Hm screen size

5.5m x 5.5m = 30.25
3.44m x 3.44m =11.83
30.25+11.83 (make sure you add not multiple)

sq root 42.08
6×6=36 to little
7×7=49 to much
6.6×6.6 = 43.56 = almost right
6.5×6.5 = 42.25 not quite
6.9 x 6.9 = 42.12 that will do
6.9m x 39.37007874 inches
= 271 inch dia screen

This online tool will also give to a quick way to establish all the measurements.

When inquiring about an IQRite Touch frame it always pays to quote the Height x Width as the final size. State whether this is the image touch area or the external frame size required.

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