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6 life size online rulers

You may think that the ruler is only for schoolchildren and carpenters. However, almost everyone needs this tool from time to time. If you don't have a real ruler, why not use a computer one?

Such rulers can be handy if no other tools are available. But there is no guarantee that the measurement results will be quite accurate. Therefore, we do not recommend using them for high-precision work. Although services and applications try to automatically calibrate so that the drawn centimeters match the real ones, they do not always succeed.

It's better to double check them for accuracy. This is easy to do with an item that has standard sizes. For example, with a banknote. So, the length of a 100 or 500 ruble note is 150 mm, and a banknote of 2000 rubles is 157 mm.


iRuler is an online service that has been operating since 2007. Having entered the site, you will see the usual ruler right on your computer screen. Measurements can be taken both in millimeters and centimeters, and in inches.

The site automatically determines the screen size and resolution to display the ruler correctly. If the function did not work correctly, click on the inscription "select your monitor dimension" to specify the diagonal and resolution manually.

On this acquaintance with this simple tool can be completed, the service has no other functions.

PiliApp Actual Ruler

PiliApp Actual Ruler is another on-screen ruler that differs from iRuler in more functionality.

When you visit the page for the first time, the service will ask you to confirm the correctness of the automatic detection of the screen diagonal. If the dimensions do not match your monitor, you can select the diagonal from the list or enter the size manually. But there is also an option "I don't know the dimensions of the monitor".

In the latter case, you can use the same banknote, credit card, or, for example, an iPhone, if you know its dimensions, to measure the diagonal. If you click on the “drag it” button, the ruler will open in a separate browser window, which can be easily moved to any desired location on the screen.


FreeOnlineRuler has additional options that the sites mentioned above do not have. With a mouse click, the ruler can be easily dragged to any place on the screen. And if you hold down the Ctrl button while clicking, you can still rotate it. This is useful for measuring objects with irregular geometric shapes.

At the bottom of the page, you can uncheck the display of centimeters or inches if you want only one measurement scale to be shown. And if you check the “flipped” checkbox, the zero mark will move to the right, and measurements will be made, respectively, from right to left.

The FreeOnlineRuler service also has a calibration tool. Click "Please calibrate your ruler" at the bottom of the screen. Here you can calibrate using a credit card, banknote or sheet of paper with known dimensions.

Ruler by Xalpha Lab

The sites described above are good for using on a computer, but not on a smartphone. If you need a ruler for your phone or tablet, you will need a dedicated app.

If you have an Android smartphone, we recommend using the application Ruler. It was highly rated by users on Google Play (almost 9 thousand users rated it 4.6 points). Drag the height and width guides to fit the size and location of the object being measured.

If you click on any free space on the screen, the top menu will open. Here you can switch to a dark theme, change units of measure, calibrate with a coin or credit card, and more.

Of course, since the display of the phone is much smaller than the size of the monitor, it is convenient to measure only small objects using the smartphone application. But in some cases, this may be enough.

Google Measure

For large objects, we advise you to pay attention to Google Measure. This is an augmented reality app introduced in 2016 that uses a smartphone's camera to take measurements. You can save photos of your measurements for later use. This is a very handy feature, especially for those who, for example, choose a sofa in a furniture store.

When used correctly, the application works quite well. In testing, he was able to correctly measure a table 182 cm wide, but he measured the protrusion on the table, which is 28 cm, as 25 cm. The application itself warns that its measurements may have an error of this very 3 cm. illuminated surfaces.

Ruler by Tue Nguyen Minh

If you have an iPhone, you will find just as many apps as Android. One of the best is 3-in-1 Ruler from Vietnamese developer Tue Nguyen Minh. This application has not only the usual on-screen ruler, but also the functionality of augmented reality and the ability to print the ruler.

When you launch the app, it will ask you to access your phone's camera. This is necessary for measurements using augmented reality. Using a regular ruler, you can measure objects with dimensions not exceeding 10 centimeters.

By the way, the latest versions of the iPhone already have a built-in application called “Measurement”. It can also use augmented reality.