Take a Visual Acuity Test Online
This visual acuity test online is an interactive Snellen-style eye chart that estimates how sharp your eyesight is. Letters appear in progressively smaller sizes, and the tool finds the smallest line you can read accurately from your chosen distance.
It works just like the chart at an eye clinic: ten acuity levels from 20/200 down to 20/10, with results shown in standard notation. It is handy for anyone curious about their vision, for glasses or contact-lens wearers checking whether a prescription still feels right, and for parents running a quick at-home screen for their children.
How to Use the Visual Acuity Test
Choose the eye and distance
Pick Left Eye, Right Eye, or Both Eyes — when testing one eye, the tool reminds you to cover the other. Then select a viewing distance of 3 ft, 5 ft, or 10 ft and sit that far from your screen.
Calibrate your screen
Drag the slider until the on-screen rectangle matches the width of a standard credit card (85.6 mm). This sets your screen's real PPI so letters display at the correct physical size.
Read each line
Letters appear largest first. Enter what you see with the on-screen buttons or your keyboard; the line submits automatically once every letter is in. Press Can't Read to skip a line you cannot make out.
Review your result
The test continues to smaller lines until you miss or skip two lines in a row. You then see your estimated acuity score (such as 20/20), a rating from Excellent to Poor, and a line-by-line breakdown.
Features
Snellen Eye Chart
Standard optotype letters across 10 acuity levels, from 20/200 down to 20/10, sized with the official Snellen formula.
Left, Right, or Both Eyes
Test each eye on its own or both together, with an on-screen reminder to cover the other eye when needed.
Three Viewing Distances
Choose 3 ft, 5 ft, or 10 ft and the letter sizes adjust automatically to your distance and screen.
Screen Calibration
Match a reference rectangle to a real credit card so letters display at their true physical size on any display.
Buttons or Keyboard
Tap the on-screen letter buttons or type directly; use Backspace to fix mistakes and Enter to submit early.
Auto-Submit Lines
Each line is checked automatically the moment you enter every letter, so there is no extra button to press.
Adjustable Button Size
Scale the input buttons from 100% up to 200% so they stay easy to tap even from far away.
Instant Line Feedback
A quick popup after each line shows whether you passed or failed along with your accuracy.
Detailed Results
See your acuity score, a rating from Excellent to Poor, what it means, and a breakdown of every line you attempted.
Frequently Asked Questions
How accurate is this online eye test?
Used correctly — with proper screen calibration and a steady viewing distance — it gives a reasonable estimate of your visual acuity. It is not a substitute for a professional exam, which also checks peripheral vision, eye pressure, retinal health, and more.
What is a Snellen chart and what does 20/20 vision mean?
A Snellen chart shows letters that shrink line by line to gauge how sharp your distance vision is. A result of 20/20 means you see at 20 feet what a person with normal vision sees at 20 feet. Something like 20/40 means you must be at 20 feet to read what a normal eye reads at 40 feet, indicating reduced acuity.
Why do I need to calibrate my screen?
Different screens have different pixel densities, so a letter that looks 10 mm tall on one display might be 8 mm on another. Matching the reference rectangle to a real credit card lets the tool calculate your screen's actual pixels-per-inch and size the letters correctly.
What distance should I sit from the screen?
The clinical Snellen test uses 20 feet, which is impractical at home, so pick the largest distance you can manage comfortably: 10 ft for the most accurate result, 5 ft as a solid default, or 3 ft when space is tight. The letter sizes adjust to whichever you choose.
Which eye should I test first?
Either order is fine — many people start with the right eye out of habit. The key is to fully cover the eye you are not testing with your palm without pressing on the eyelid, then repeat for the other eye.
What does "Can't Read" do?
It skips the current line and marks it as not passed. If you skip or fail two lines in a row, the test ends automatically and uses your last passed line as your result.
Can I retake the test?
Yes. After your results, choose Test Again to return to the setup screen. The letters are randomized each run, so no two tests are identical.
Is my data stored anywhere?
No. All processing happens entirely in your browser. Nothing is sent to a server, and your results are not kept after you close the page.
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