100,000 - 500,000 downloads

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Photo Ruler is designed to accurately measure the size of any object by taking a picture of it. With its simple user-friendly design Photo Ruler allows you to measure things just as conveniently and precisely as with a traditional ruler or tape measure.

How to use:

Firstly, please ensure that the object you wish to measure and the object of known length (Base Item) are in the same picture. There is a predefined list of Base Items, including Debit/credit card and Quarter. Select the one you have.

Secondly, ensure that the Base Item and the object you wish to measure are in the same plane and the camera is (or was) parallel to them. This is necessary to avoid image distortions caused by the camera perspective.


It is advised to use the Base Item which is closest in size to the object you wish to measure. Given that you have accurately aligned markers, you will receive a measurement that is as precise as when using a traditional ruler or tape measure.

Tags: photo ruler, ruler free.

Recently changed in this version

Minor bug fixes

Comments and ratings for Ruler
  • (53 stars)

    by Marvin Bodden on 18/12/2013

    I love this app I rate 5 stars

  • (53 stars)

    by James Lim on 13/12/2013

    This app is excellent! I highly recommend it!

  • (53 stars)

    by surawut charoen on 01/12/2013


  • (53 stars)

    by waseem akram on 24/11/2013

    Wo ho amazing, superb. Great work dude keep it up. :*

  • (53 stars)

    by Jason Morgan on 19/10/2013

    Works great. Was just what I was looking for.

  • (53 stars)

    by Fatima Ali on 02/10/2013

    I don't know how to add a label or whatever it's called

  • (53 stars)

    by James Bradley on 22/08/2013

    Can't get the app to work, it keeps asking me to force close any other app using the camera, and having done that it still says the same, so far just useless for my HTC one. I can't see how to get help either.