My 15.6 laptop display is being detected as 22.9. Why?

I have a Lenovo IdeaPad U530. It has a 15.6" display. I was checking out iruler.net, and the website believes that my display is 22.9." http://www.infobyip.com/detectdisplaysize.php does the same thing.
How can I fix this? Is it a problem with my browser, or with my computer?
I will do some more digging while I wait for a response. Thanks guys.

Added (1). Update: Using Chrome, it is detected as 22.9." Using IE, it is detected as 18.4." *confusion intensifies*

Guest

Because you're not reading what it says on the screen, mate.

On iruler.net it stated that my monitor dimernsion was 13.3", but if you look immediately below this it says If you have different display select your monitor dimension

If you know that your laptop's display is 15.6" you select that.

micksmixxx