What is 20/20 Vision?
What is 20/20 Vision?
20/20 vision means having normal visual acuity — the ability to see clearly at a distance of 20 feet (6 metres). While it is often described as “perfect vision”, 20/20 vision does not mean your eyes are completely free from problems or that you will never need glasses.
How well you see is known as visual acuity. Visual acuity is measured on a Snellen chart, with 20/20 being considered normal vision.
A Snellen chart consists of rows of letters, with each row getting progressively smaller in size. To qualify as having normal or 20/20 vision, a person must be able to see the smallest row of letters at 20 feet (6 metres) as labelled on the chart
What do different vision scores mean?
A 20/20 vision score means you can see clearly at 20 feet what someone with normal visual acuity can see at that same distance.
Vision scores compare how clearly you see from a certain distance with what is considered normal vision.
For example:
- 20/40 vision means you can see at 20 feet what someone with normal vision can see at 40 feet (12 metres).
- 20/100 vision means you can see at 20 feet what someone with normal vision can see at 100 feet (30.5 metres).
A lower vision score does not necessarily mean your eyes are unhealthy, but it may indicate you need glasses, contact lenses or other treatment to improve your vision.
What does 6/6 vision mean?
In Australia and New Zealand, visual acuity is measured using the metric system rather than feet. Instead of 20/20 vision, normal vision is often described as 6/6 vision.
Someone with 6/6 vision can read the smallest row of letters on a Snellen chart from a distance of 6 metres. It means the same thing as 20/20 vision — normal visual acuity measured using a different distance system.
Is 20/20 vision the best eyesight possible?
20/20 vision is considered normal vision, but it is not necessarily the sharpest eyesight possible.
Some people have better-than-average visual acuity. Eagles, for example, are often said to have “eagle eye” vision because they can see much further and in greater detail than humans.
Eagles have been estimated to have vision around 20/5 or 20/4. The best recorded human visual acuity is around 20/10, meaning the person could see clearly at 20 feet what someone with normal vision would need to move closer to see.
Do you need glasses if you don't have 20/20 vision?
Not necessarily.
Having less than 20/20 vision does not automatically mean you need glasses. An eye health professional can assess your visual acuity and determine whether glasses, contact lenses or another treatment may help.
There are many reasons someone may need glasses, including refractive errors such as:
- Short-sightedness (myopia) — difficulty seeing distant objects clearly.
- Long-sightedness (hyperopia) — difficulty seeing nearby objects clearly.
- Astigmatism — blurred or distorted vision caused by an irregularly shaped cornea.
Many people also need glasses as they get older due to presbyopia, a gradual loss of the eye’s ability to focus on nearby objects.
Can you have 20/20 vision and still have eye problems?
Yes.
Visual acuity only measures how clearly you can see at a distance. It does not measure every aspect of eye health.
Someone can have 20/20 vision and still experience other eye conditions that affect things like:
- peripheral vision
- eye pressure
- colour vision
- overall eye health
Regular eye checks are important because some eye diseases can develop without obvious changes to your vision.
What vision level is considered legally blind?
Legal blindness is determined differently depending on the country and healthcare system.
In many places, a person is considered legally blind when their vision remains significantly reduced even after correction with glasses or contact lenses, or when they have a severely restricted field of vision.
Someone with legal blindness may only be able to read a sign from 6 metres away that someone with normal vision could read from 60 metres away.
Frequently asked questions about 20/20 vision
Does 20/20 vision mean perfect eyesight?
No. 20/20 vision means you have normal visual acuity, but it does not mean your eyes are completely free from eye conditions or that your vision will never change.
Can your vision improve to 20/20?
Some people can achieve 20/20 vision with glasses, contact lenses or treatment. Whether vision can improve depends on the cause of reduced eyesight.
How is 20/20 vision tested?
20/20 vision is tested using a Snellen chart during an eye examination. The chart measures how clearly you can see letters at a set distance.
DISCLAIMER: The content on this page is not intended to be medical advice. For specific medical advice, please contact your health professional.
Last updated: 5 August 2026
Meet the author
Dr Lila Raj Puri
Dr Lila Raj Puri is a Medical Adviser at The Fred Hollows Foundation, and his interest lies in research and training. Based in London, he advises on national prevention of blindness strategies in the Asia region, and leads the development and implementation of clinical governance frameworks. He also supports ophthalmologist training and quality assurance at Alina Vision Hospital. He is an ophthalmologist with over 12 years of experience in clinical and surgical management of eye diseases, and hospital management. As an Associate Professor, he has trained national and international ophthalmologists in cataract surgeries, as well as overseeing the training of optometrists, residents and nurses.
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