So, for example what 800px (that is my average page width) in percentages? I have tried to work it out by dividing 145px by the amount of space I have to fill, which is 655px; because the whole resolution for the width is a minimum of 1024 by 768px:

 

The formula is:

Method: (X / Y) * 100 = R

Example: 3 / 26 = 0.11 | 0.11 * 100 = 11%

 

[i also found a formula for text on webinmind.net]

Examples:

* For a 13px text: 13 / 16 = 0.8125 = 81.25%

* For an 18px text: 18 / 16 = 1.125 = 112.5%

 

... I tried the text but, it's a little screwy in IE. (Like we expected any different =D)

 

Enjoy mien fellow interwebbers, this is a beta thing for me too, if you spot an error, jump all over it ^^

Percentages are based on the size of the parent element. If you have a div set to 1000px and want to size a div within it to 800px using percentages, you would need a value of 80%. If the parent element is the body tag, a value of just under 80% (roughly 78%) is needed on 1024x768 monitors and a value of about 60% is needed for 1280x1024 monitors, assuming that the window is full-screened.

 

I'm not sure where you're getting the value 145px from, but if you know this value and want it to remain constant (for example, if it's a side bar) then I'd recommend simply using pixel sizes.

 

Font-sizes work in a similar way, but 100% is the full size of a letter in the parent element, as opposed to the height of the parent element itself. If it's a help, the default size of text in the body tag is 16px and a lot of style sheets start with this rule to re-sze that to 12:

body {font-size: 62.5%;}