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OnScreenRuler is a simple online ruler that lets you measure things directly from your screen.

We built it for those small moments when you need a ruler but don't have one nearby. Maybe you're checking the size of a small object, working on a craft project, looking at a design, or simply want to get a quick measurement without opening an app or downloading anything.

The ruler works right in your browser on phones, tablets, laptops, and desktop computers.

Why We Built It

A physical ruler is easy to use when you have one on your desk. But when you don't, finding a ruler app, installing something, or searching for a suitable tool can feel like unnecessary work.

We wanted something simpler: open the website, set it up, and measure.

That's the idea behind OnScreenRuler.

How It Works

A screen is made up of pixels, but the physical size of those pixels is different from one device to another. That's why an online ruler needs to be calibrated when you're measuring a real world object.

OnScreenRuler gives you a few ways to do this, including automatic device detection, choosing your device, entering your screen size, or using a standard bank card as a reference.

Once the ruler is calibrated, you can place an object next to it and take your measurement.

If you are measuring something that already exists on your screen, you can also use the pixel ruler without needing to convert the measurement into a physical unit.

Choose the Measurement You Need

Different situations call for different units.

If you normally work with imperial measurements, you can use our inch ruler.

For everyday metric measurements, the centimeter ruler is often the easiest choice.

When you're measuring something small and need a finer scale, try the millimeter ruler.

And if you're working with images, websites, graphics, or other things on your screen, the pixel ruler can be more useful.

You can also return to the online ruler and switch between the available units whenever you need to.

Built for Simple, Everyday Measurements

OnScreenRuler isn't intended to replace professional measuring equipment.

It's a convenient tool for quick measurements when a physical ruler isn't available or when you simply want to check something on your screen.

For work where a tiny difference matters, we recommend checking the result with a physical ruler, caliper, or another suitable measuring instrument.

No App, No Account

There is nothing to install and no account is required to use the ruler.

Just open OnScreenRuler in your browser and start measuring.

We aim to keep the tool straightforward, useful, and easy to access.

Have a Suggestion?

OnScreenRuler is an ongoing project, and we're always interested in hearing how people use it and what could make it better.

If you have a suggestion, find something that doesn't work as expected, or simply want to get in touch, you can contact us.

For information about how the website handles data and privacy, see our Privacy Policy and Terms of Use.