7 Tools to Measure Length, Width and Height on Your Computer Screen

If you want to know the dimensions of a physical object, you wouldn’t necessarily think of turning to your computer 1st to get some measurements. Of course there are tools around that can easily tell you how many pixels on the screen it is from one point to another, but actually measuring something in inches or centimeters is a little more tricky.

Whether you want to find out if a button is placed correctly on a webpage, or an object is in the correct position in your graphic work, or even if you want the dimensions of a real object but don’t have a ruler or tape measure to hand, there are utilities available to help you out. Here’s 7 tools to help you find out a variety of different measurements either in the real world or virtually on the screen.

Important Note:

If you’re going to use one of these rulers for a more accurate measurement or to measure a real world object against it, the ruler needs to be calibrated so the inches / centimeters are correct. This will differ from screen to screen because of different resolutions and monitor dimensions etc. For the best results you need to know the resolution of the current display (ie; 1920×1080) and the monitor’s exact diagonal size in inches. (ie; 23.5″). Using a value of 22 inches when your monitor is actually 21.5 will still produce a slightly inaccurate measurement and needs to be as exact as possible.

Once you have this information, visit the PPICalc or DPI / PPI Calculator webpages and enter the horizontal and vertical resolutions and the diagonal size.

Calculate and show PPI

This will output a Pixels Per Inch (PPI) number on the page which you can then enter into the ruler utility if it allows you to for the most accurate measurements. Most of the tools that allow this will let you enter only a whole number without decimal places which although not 100%, is still very close.

1. JS Screen Ruler

JS Screen Ruler

JS Screen Ruler can display pixels, inches, pica’s or centimeters and the size of the ruler can simply be extended by dragging the small slider. The right click menu gives you the options to flip the ruler from horizontal to vertical, mark the exact center of the ruler, snap it to the left edge of your desktop screen and set the pixels per inch for a more accurate measurement as mentioned above. There is also the shareware Pro version in the zip archive which has a 15 day trial although it only offers functions like color changing and ruler rotation which you probably won’t need. JS Screen Ruler is portable and works on Windows 95 up to 7 64-bit.

Download JR Screen Ruler

2. iRuler.net


iRuler is a plain and simple webpage with a static ruler which you can measure real world objects against, or resize the browser window and drag it to where you want. Make sure to check your monitor dimensions are correct under the ruler. If they aren’t, click the link to select from a small list, or select “even more” to enter your own and input the diagonal size of the monitor and its aspect ratio. If you don’t know the aspect ratio, take the monitor’s horizontal resolution and divide by its vertical resolution (ie; 1680/1050). 1.6 will be 16:10 and around 1.78 is 16:9.

Visit iRuler.net

3. A Ruler for Windows

A Ruler for Windows

This measurement utility is more of a web or graphic design tool because it only measures in screen pixels and not centimeters or inches etc. The ruler itself comes with 4 different skins to choose from, there is a reading guide mode which turns off the numbers and markers so you can use it to read documents or books with, the ruler can be flipped into vertical mode and resized or locked into position. There is also a zoom mode which can zoom into your desktop up to 4x to get more accurate measurements. Works on windows 2000 up to Windows 8.

Download A Ruler for Windows

4. NRuler


NRuler is a Java application which requires the Java Runtime Environment v6 or higher to run. It defaults to displaying both horizontal and vertical rulers at once, each of which can be hidden and independently measure in pixels, inches, centimeters and pica’s. The rulers can be accurately moved around the screen a pixel at a time if needed using the keyboard, there are markers to mark the center of the ruler or a specified distance, and a useful converter can quickly convert from one of the supported measurements to another. Works on Mac and Linux in addition to Windows.

Download NRuler

5. On-Screen Ruler

On-Screen Ruler

On-Screen Ruler is another simple measuring tool that can display the measurements in inches, centimeters, pixels, pica’s or a percentage. It also has a transparency slider option and the font and colors can be configured to your liking. The ruler can simply be resized by dragging it from the edges, multiple rulers can be used by pressing Ctrl+N to show another on screen. There is an option to calibrate the ruler but this is only by means of a couple of arrows and there is no function to set the calibration using pixels per inch. This means you won’t know for sure whether this ruler is accurate unless you physically measure it with a real or other properly calibrated virtual ruler. A portable version is available.

Download On-Screen Ruler

6. MB-Ruler


There are quite a lot of advanced options available in MB-Ruler, and in addition to measuring distances from one point to another using 6 different scales of measurement, it can also calculate angles with a protractor and includes its own sophisticated coordinates measuring system. The interface is a semi transparent set square in which the center acts as the starting point for measuring and is simply grabbed and dragged around the screen to change the start point. Other notable features include a color picker, screen capture, a grid system with snapping, screen loupe function and overlayed shapes and lines or points etc can be placed around the screen. A standalone version can be create from the options menu.

Download MB-Ruler

7. Cool Ruler

Cool Ruler

Cool Ruler is a very old utility but still seems to install and work fine on Windows 7 32-bit although 64-bit didn’t work. Unlike some of the tools here, it can create a custom ruler to match the pixels per inch of your screen to give more accurate measurements. Just go to Custom settings and enter your PPI in the Unit Size box. There is also a handy calculator built into the program, multiple rulers can be added to the desktop, markers can be created and the fonts can be altered if they’re a bit small.

Download Cool Ruler

8 Comments - Write a Comment

  1. Mike 1 month ago
    • HAL9000 1 month ago
  2. George 5 months ago
  3. David 8 months ago
  4. Rain Wilber 1 year ago
  5. alex 4 years ago
  6. mahzam 13 years ago
  7. ma7moud 13 years ago

Leave a Reply

Your email address will not be published. Required fields are marked *

Note: Your comment is subject to approval. Read our Terms of Use. If you are seeking additional information on this article, please contact us directly.