OMR stands for Optical Mark Recognition: software that looks at a page, finds the places where a person has filled in a mark, and turns them into data. Every multiple-choice exam answer sheet you have seen — the rows of small circles — is an OMR sheet. The “reader” used to be a machine. Today it can be the camera in your phone.

OMR in one paragraph

An OMR sheet has a fixed layout: every question has a known row, every option a known position. A reader does not “understand” the page; it checks, for each position, whether it is dark enough to count as a mark. Because the layout is fixed, the job is quick and reliable — which is why OMR is used for entrance exams, school tests and surveys.

How a phone reads a sheet

  1. Find the page. The printed black frame and four corner marks tell the app where the sheet is.
  2. Straighten it. A photo taken at an angle is corrected so it looks like a flat scan.
  3. Locate every bubble. Edge marks and coded tags tell the app which row is which question.
  4. Measure darkness. Each bubble is checked; a filled one is clearly darker than an empty one.
  5. Compare with the key and apply the marking rules, including negative marking.

ScanScore does all of this on the phone in about four seconds, with no internet. The accuracy guide covers the checks that stop a bad photo becoming a wrong mark.

OMR is not OCR

OCR (optical character recognition) reads text — printed or handwritten letters. OMR only decides whether a mark is present. That is why OMR is far more dependable for multiple-choice answers than trying to read handwriting. If you do want to read a printed answer key from a photo, that is a separate feature; see reading an answer key from a photo.

Where OMR is used

  • School and college multiple-choice tests
  • Competitive-exam mock series, such as NEET and JEE practice
  • Surveys, attendance and feedback forms

Machine or phone?

A traditional OMR machine needs pre-printed forms and a trip to wherever the machine is. A phone needs a printer and ordinary paper. The trade-offs are laid out in phone versus OMR machine.

Try it in ten minutes

Install ScanScore from Google Play (Android 7.0+), make a five-question exam, print the sheet and scan it. Setup is walked through in the step-by-step guide, and students can learn the filling rules from how to fill an OMR sheet.

Keep reading: AI OMR checker online