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Online Vision Test

Calibrate your screen, choose a distance and pick the side where each ring is open. Treat the result as a rough guide only.

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1. Calibrate your screen

Hold a credit card or ID card (85.60 × 53.98 mm) against the screen and move the slider until the outer edge of the dashed box matches the card.

Hold your card here

2. Set up the test

3. Test

Press “Start test” and a ring will appear here.

You can also answer with the arrow keys. For diagonals use numpad 7, 9, 1 and 3; press 5 or Space if you are not sure.

This is a rough screen-based check that depends heavily on your display, lighting and distance. It is not a medical exam. If your vision has changed or your eyes feel uncomfortable, see an optometrist or eye doctor.

How to use

  1. Each ring’s gap is drawn so that at 1.0 (20/20) it spans one arcminute: gap = distance × tan(1′ ÷ acuity). The ring is five gaps wide.
  2. Start by matching the dashed box to a real card. The tool needs your screen’s true size to draw rings at the intended size.
  3. Pick a distance, sit that far away, cover one eye with your palm and press Start. From 2 m on, ask someone to press the buttons or use a wireless keyboard.
  4. Choose the side where the ring is open. Get 3 of 4 right and the rings get smaller; the last level you pass is your estimate.
  5. Test in a bright room wearing your usual glasses or contacts. The result is only a guide and never replaces an eye exam.

FAQ

Can I rely on this like a real eye exam?

No. Screen brightness, pixel size, the real distance and lighting all change the result. Use it only to notice rough changes, and see an eye care professional for a proper exam.

What if I do not have a credit card?

Most plastic cards, such as driver’s licences, ID cards and transit cards, use the same ID-1 size. With a ruler you can also set the dashed box to exactly 85.6 mm wide.

Do I need to calibrate again after zooming?

Yes. Browser zoom and display scaling change how big the rings are drawn. Your calibration is saved in the page address, so reopening that link on the same device restores it.

What does 20/20 mean?

It means you can see at 20 feet what a person with typical vision sees at 20 feet. It equals decimal acuity 1.0, and is written 6/6 in metres.

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