There was something about this question, that made me realize that, I have been using a Firefox add-on that helps users to measure pixels on a webpage, in a quick and easy way for ages now.
The Web Developer extension for Firefox is something I rely on quite often for several reasons, I feel will not fit this post, but to answer this certain question, you can easily measure pixels on any webpage using the Web Developer add-on.
If you do not already have this useful add-on installed in Firefox, download it first and then visit the toolbar or the Tools menu and click on Miscellaneous > Display Ruler.
Once you have enabled the ruler you can measure any object on the webpage to determine the exact pixels used for the HTML object. Take a look at the screenshot below to see how much pixels are used to display the Techie Buzz logo.
This is one extension we would recommend to everyone, there are several other features which come in really handy and can make it a must have Firefox add-on.
We have a compiled list of cool Firefox add-ons for programmers and designers coming up soon, it’s been on a backburner, but this question has led me to work and publish that post faster, so stay tuned and visit back regularly.