Is this online eye test accurate?

It provides a reliable estimate. The Landolt C is calibrated to your exact screen size using a US quarter, so the symbol appears at its correct physical size. Room lighting and screen brightness can introduce minor errors. Use this as a guide, not a clinical result.

What does 20/20 vision mean?

20/20 (Snellen) means you can read at 20 feet what a person with standard vision reads at 20 feet — equal to 1.0 in decimal notation. 20/40 means you need to be at 20 feet to see what most people see at 40 feet (decimal 0.5).

Does this eye test work on iPhone and Android?

Yes. The tool runs in any modern browser — Safari on iPhone or Chrome on Android. No app installation is needed.

What are the different test distances for?

10 ft (3 m) approximates the standard clinical eye chart distance. 12 in (30 cm) checks near vision for reading or phone use. Choose the distance that best matches your daily activity.

My result seems worse than usual — what should I do?

First ensure your screen is at full brightness in a well-lit room. If results remain low compared to your last eye exam, schedule a visit with an optometrist. Early detection of vision changes is important.

Free Online Eye Test — Vision Check in Your Browser

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Calibrate your screen with a US quarter (24mm), then check your vision with a Landolt C chart at 3 m, 1 m, 20 in, or 12 in. Results shown in both decimal and Snellen (20/20) notation.

How to Use This Eye Test

This free online eye test runs entirely in your browser — no app download required. Because every phone screen is a different size, we first calibrate using a US quarter (diameter: 24.26 mm). Once calibrated, the tool displays a Landolt C (the international standard eye-test symbol) at the correct physical size for your chosen viewing distance. Choose the gap direction you can just barely make out, and your vision score is displayed in both decimal and Snellen (20/20) notation.

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STEP 1: Calibrate Your Screen

Place a US quarter (or any coin of known size) on your screen. Drag the slider until the circle matches your coin exactly.

Place quarter here

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About the Landolt C Chart

Why a Landolt C?

The Landolt C (or Landolt ring) is the international standard for visual acuity testing, adopted by the International Council of Ophthalmology. Unlike letter charts (Snellen letters), it works equally well regardless of your native language or literacy.

Decimal vs. Snellen

European and Asian countries often use decimal notation (e.g., 1.0), while the US uses Snellen fractions (e.g., 20/20). Both mean the same thing — you can read at normal distance what a person with standard vision reads. This tool shows both.

What to Do If Your Vision Seems Low

This tool gives you a quick estimate, not a diagnosis. If your results are lower than expected or you notice blurry vision in daily life, we recommend:

Visit an eye doctor: An optometrist or ophthalmologist can give you an accurate prescription and check for conditions like glaucoma or macular degeneration.
Review your glasses or contact lens prescription: An outdated prescription causes eye strain. If you haven't had a check-up in over a year, it's worth going.
Try contacts online if your prescription is current: If you already know your prescription, buying contacts online can save money. Note: always get a valid prescription first.

This page and tool are not intended for medical diagnosis or treatment. If you experience eye discomfort or sudden vision changes, please consult a healthcare professional immediately.

Frequently Asked Questions

Q. Is this eye test accurate?: It's a reliable estimate. We calibrate the Landolt C to your exact screen size using a coin, so the symbol is displayed at its correct physical size. That said, room lighting, screen brightness, and protective film can introduce small errors. Use this as a guide, not a clinical result.
Q. What does 20/20 vision mean?: 20/20 (Snellen) means you can clearly read at 20 feet what a person with standard vision reads at 20 feet — it equals 1.0 in decimal notation. 20/40 means you need to be at 20 feet to see what most people see at 40 feet (decimal: 0.5).
Q. Does this work on iPhone and Android?: Yes. The tool runs in any modern browser — Safari on iPhone or Chrome on Android. No app installation needed.
Q. What are the different test distances for?: 10 ft (3 m) approximates the standard distance used in most clinical eye charts. 12 in (30 cm) checks near vision — useful for reading or phone use. Use whichever matches your daily activity.
Q. My result seems worse than usual — what should I do?: First, make sure your screen is at full brightness and the room is well lit. If results are still low compared to your last eye exam, schedule a visit with an optometrist. Early detection of vision changes is important.