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How to find the prescription number from glasses

Losing a prescription of any sort is a problem but if you happen to have lost the prescription for your glasses, all is not lost. To get a certified, doctor-approved prescription, you will need to visit the doctor again but you can also find the prescription from a pair of glasses if their lens is intact.

If you already have a pair of prescription glasses, you can take them to an optician who will examine them and give you the exact prescription number. If that isn’t an option, you can do an at-home test.

Find prescription number from glasses

In order to find your prescription from a pair of glasses at home, you need;

  • A computer.
  • A phone, Android or iPhone.
  • A credit card, or similar for calibration (the process is free).
  • Something to mount your phone on to keep it stable since you will be holding your glasses during the test.
  • A well-lit room.

Install Lingo Rx

  1. On your phone, install the Lingo Rx app. It’s available for Android and for iOS.
  2. Once the app is installed, visit this page.
  3. Scan the QR code on the page with the Lingo Rx app.
  4. Once the scan is complete, calibrate the size of your screen using the credit card.
  5. Place the credit card inside the grid of dots, and scan it with the app.
  6. Once calibration is complete, you can start the test.

Check prescription number 

Before you start the test, you must know that the six dots on the screen that you see must be visible to the app on your phone at all times. They should not fall outside the ‘visible’ area for the app and they should not be obstructed by your hand or glasses.

  1. Position your phone in front of your screen. The app will guide you if the phone is too close or too far away.
  2. Take off your glasses, and hold them between the phone and the screen. Make sure the ‘eyes’ on the screen are visible through the glasses.

  1. Follow the app’s instructions and move your glasses close or away from the screen. Tilt it when prompted to.

  1. Once the scan is complete, the app will analyze it. 
  2. Take a selfie with a credit card when prompted. 
  3. The results will be displayed on your computer.


We tested this app out and it was 100% accurate. The numbers shown were consistent with the numbers from an eye exam done by an optometrist. 


This method and this app have limitations which it clearly states on its home screen; it cannot scan glasses if the prescription falls outside the -6.00 to +3.00 range, and for cylinder values that exceed -2.5. If any/either of these values exceed the range, the scan will fail.

We tested this as well and found it to be true but that’s hardly a surprise. Numbers that exceed -6.00 are considered extreme myopia. The +3.00 range is conservative though since +5.00 is what is considered extreme in hyperopia. Scanning them with accuracy is not possible with just a phone.

Need to test your hearing? There’s an app for that.

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