Measure anything your iPhone can take a picture of.

“ of the coolest apps I have seen so far.”

“...the best ruler app for the iPhone.”

“...unique app, accurate measurements.”

“ of the few apps that I keep on my personal iPhone.”

“RulerPhone will inevitably come in handy, so you might as well buy it now!”
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RulerPhone has now been downloaded by hundreds of thousands of iPhone and iPod Touch users.

New Version! RulerPhone 2.0 can also measure the distance between your iPhone's camera and any object as well as save any measurement to your photo library!



RulerPhone turns your iPhone and its camera into a measuring tape -- all you need is an item that you probably carry around with you already: a gift card, MetroCard, driver's license, or anything with the exact dimensions of a credit card.

  1. Picture
    Place your credit-card sized card right next to or in front of the object you would like to measure. Take a picture of the object, trying to keep the credit card centered in the frame. Make sure your card and object are facing directly at the camera. Note that you can either take a picture directly in RulerPhone or access your photo library to measure saved photos.

  2. Position
    You need to align the card in your photo with the blue card placeholder that RulerPhone displays on the screen. To do this you will need to zoom and drag your photo, and you can also rotate the blue card placeholder to help. It is important that you zoom the image until the card in your picture is the same size as RulerPhone's blue card placeholder, since this is the reference that RulerPhone uses to measure objects in the frame.

  3. Measure
    Once the cards are aligned click "Lock Card" or "Measure" to begin accurately measuring the object in your photo. Drag your finger across the screen to measure distances, and you will see a measuring tape appear across the screen. Drag the ends of the measuring tape to fine-tune your distance, and zoom the picture in and out by pinching or pulling to help you get a better view.

  4. If you are having trouble with accuracy, read the tips section for all the do's and don't's of RulerPhone.


  • Video review of RulerPhone by
  • In-depth video review of RulerPhone by iPhoneAppPodcast
  • Screencast of RulerPhone in action, being used to measure the width of bedroom windows:


The following tips are crucial to achieving accurate measurements. If you are having trouble with accuracy, it is probably because you are not following one of these pieces of advice. In testing, RulerPhone is able to take measurements up to and exceeding 12 feet with errors ranging from 0.5 to 1.5 inches when these tips are closely followed.

  1. Point your camera directly at your card
    If your card or object being measured is angled away from the camera such that the card has depth in the picture, RulerPhone's measurements may be inaccurate. Make sure that the camera is pointing directly at both the card and your object being measured.
  2. Center your card in the shot
    Although it is possible for RulerPhone to take accurate measurements when the card in your picture is significantly off-center, you will find that accuracy improves if pictures are taken with your card centered.

  3. Place your card directly on the item being measured
    If your card is placed significantly in front of or behind the item being measured, RulerPhone will not have an accurate frame of reference and your measurement may be inaccurate.
  4. Align your picture's card with RulerPhone's card closely
    Carefully zoom your picture until the two cards are perfectly aligned for the most accurate measurements. The alignment of these cards is where RulerPhone gets its frame of reference, and an improper alignment may result in incorrect measurements. This also explains why RulerPhone's accuracy will continue to increase as the iPhone's camera improves: with higher-resolution pictures, users have more control over perfectly aligning the cards.


  1. Can I just try it out?
    Of course. RulerPhone Lite is available for FREE on the App Store, and the Lite version lets you measure anything up to 1.5 feet.

  2. When are metric units going to be available?
    Right now. The latest update of RulerPhone includes metric support and is available to all RulerPhone owners, for free, via the App store.

  3. Does RulerPhone work with the iPod Touch?
    Yup! Although you won't be able to take any pictures since the Touch doesn't have a camera, both the Touch and the iPhone can use any of the pictures in your photo library.

  4. Can I help with translation?
    Yes! And you can get a free version of RulerPhone while you're at it. The latest version of RulerPhone includes Spanish, French, Dutch, Chinese, and German localization thanks to the help of happy RulerPhone users. If you would like to translate RulerPhone to your own language, just email me at the contact address. I'll send you an iTunes gift card for your trouble.

  5. How is RulerPhone being received?
    Very well. I've heard from casual users, architects, interior decorators, event planners, and more who all report successful (and fun!) experiences with RulerPhone. If you have a story, comment, or even an improvement you'd like to share, please contact me.


Feel free to email me with questions or suggestions at kamens ·at·