50,000 - 100,000 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
  • (58 stars)

    by Stephan LaBar on 01/07/2014

    Connot believe what this app does!

  • (58 stars)

    by Ian James on 30/06/2014

    Measured a 4 foot box 3 inches

  • (58 stars)

    by Kimberly Lee on 24/05/2014

    Must download very accurate but has to take shot n find the photo only then can measure.

  • (58 stars)

    by Rio Wong on 19/05/2014

    Always 3.37" no matter what I photoing measure?

  • (58 stars)

    by Budi Lisdinanto on 09/05/2014


  • (58 stars)

    by Robert Hughes on 30/04/2014

    This app is highly helpful, I tend to use it for measuring the fish I catch. The issue I'm having is when I cannot measure an item from a selected file. I have to use the app to take the picture. It says "string path null" if you could fix this please I would give it 5 stars for doing exactly what its supposed to

  • (58 stars)

    by Joseph Ruhl on 21/04/2014

    Wish I thought of this.