# Have you ever wondered why manufacturers use screen diagonal as a measure of screen size?

#### alexeysalo

##### Member
Hello, everyone!

Just wanted to share some thoughts with you or maybe an advice: don't care too much about screen diagonal, because it's a pretty misleading metric today.

The 5.8" iPhone X screen is physically smaller than 5.5" iPhone 6 Plus screen, and the 6.2" Galaxy Fold 3 screen is 30% smaller than 6.0" screen of most eBook readers.

What's more important is the angle of diagonal! We can have two identical diagonals and completely different "amount of screen":

So, don't be fooled by the diagonal size. If you want to know actual amount of screen, use screen area instead, i.e, screen_height * screen_width. And to calculate height and width of the screen, use this simple formula:

where d is diagonal, a and b are the aspect ratio.

For instance, this is how you can calculate screen size of the iPhone 13 Pro Max:

If you calculate, you get the results: screen area is 17 square inches or 110 cm[SUP]2[/SUP]. Now calculate any other smartphone's screen and compare their areas!

Hope, that was helpful! Did you ever thought about that?

*taking from here.

#### L0n3N1nja

##### Well-known member
Never really thought about it as we've been measuring TV screens by their diagonal measurement since long before I was born and it carried over to computer monitors and other screens.

#### spARTacus

##### Well-known member
Nice reminder. Always remember to also consider screen aspect ratios if one is thinking about diagonal measurements for comparison purposes.

#### methodman89

##### Well-known member
It makes great sense, a standard, which cynically is why it won't happen

#### alexeysalo

##### Member
Okay, now what about screen brightness?

A lot of people assume that 1400 nits is twice as bright as 700 nits, and 700 nits is twice as bright as 350 nits. So when we see that the iPhone 13 Pro Max screen brightness is 1200 nit and the Galaxy S22 Ultra is 1750 nit, it might seem as if the Galaxy S22 Ultra screen is almost 50% brighter. But in reality this is not the case at all.

The fact is that humans perceive brightness on a logarithmic scale, that is, if we were to place brightness values of 1, 10, 500, 1000 and 1500 nits on the scale, it would not look like this:

It would look like this (that's how we perceive brightness):

In other words, the difference in brightness between 1 and 10 nits is much larger than the difference between 500 and 1500 nits, although we only added +9 nits in the first case, and +1000 nits in the second.

If the brightness of your smartphone screen is 1000 nits, you need a screen with maybe 4000 nits or even higher, in order to make the brightness appear twice as much. So, don't take the bait and don't trust manufacturers who want you to believe in specs!

#### B. Diddy

##### Senior Ambassador
Moderator
Very cool info, thanks!

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