MeasureIt is one of those simple, effective tools that can help newbies and experts measure screen elements in pixels - on the fly. For graphic layout and online work, keeping track of size has not always been easy until now.

Once MeasureIt is installed it is easy to draw a ruler across any webpage to check the width, height, or alignment of page elements in pixels.

ruler extension

Using MeasureIt is easy:

  1. Click the MeasureIt button in the status bar or toolbar to turn it on/off.
  2. Click and drag out a ruler box.
  3. Click and hold to move the ruler box.
  4. Use CTRL + Arrow Keys to nudge ruler by 1 pixel.
  5. Use CTRL + SHIFT + Arrow Keys to nudge ruler by 5 pixels.
  6. Click the "X" to close that ruler or click outside of it to begin drawing another ruler.
  7. Use the ESC key to turn off  MeasureIt.

Once installed, there is nothing more to do. The trick for those new to Firefox is to find the small icon in your status bar in the bottom left hand corner of the screen - and then begin measuring!  To use this extension the Status bar must be activated, which is done in the View menu.

ruler extension

Features:

  • instant click and drag pixel measurement tool.
  • one click on-off function.
  • keyboard adjustment on screen position 1 or 5 pixel increments.
  • Similar web tools: Screen-o-Meter.

Check out MeasureIt @ addons.mozilla.org/en-US/firefox/addon/539 [No Longer Available]