Printable Eye Chart (Snellen): Free PDF + On-Screen Test
Download a Snellen-style eye chart PDF, print it at the right size and test at the right distance. Instructions included.
This is a screening tool, not a medical diagnosis. Results depend on your screen, brightness and lighting. See an eye doctor for a proper exam. Medical disclaimer
Last updated: . Based on the sources listed below.
Download the chart
- 10 feet (3.05 m) · A4PDF · 1 page
- 10 feet (3.05 m) · US LetterPDF · 1 page
- 20 feet (6.1 m) · A4PDF · 2 pages
- 20 feet (6.1 m) · US LetterPDF · 3 pages
Print at 100% / Actual size. Then measure the 100 mm scale and the 30 mm square with a ruler. If they are not exact, change your print settings and print again. Printing size must be checked: we cannot know your printer. Letters are drawn by us as vector shapes; we did not copy a commercial chart.
How to use the printed eye chart
- Print at 100%. In the print dialog choose “Actual size” or “100%”, never “Fit to page”.
- Check the scale. The 100 mm line and 30 mm square at the bottom must measure correctly with a ruler.
- Hang it. Tape the chart to a wall at about eye level in good, even light.
- Measure the distance. Stand exactly 10 feet (3.05 m) or 20 feet (6.1 m) away, as printed on the chart. Use a tape measure.
- Cover one eye. Wear your usual glasses if you have them. Cover one eye with your palm without pressing, and read each row from the top until you miss more than half of a row.
- Test the other eye the same way.
Clinics test each eye separately, right eye first by convention, and read line by line until more than half of a line is missed (EyeWiki: Visual Acuity Testing in Adults). The row where you stop is a rough reading only and not a medical test.
What do the numbers on the chart mean?
Each row is labeled with a Snellen fraction in feet and in meters, for example 20/40 (6/12). Snellen letters are built so that the stroke is one fifth of the letter height, and the whole letter subtends 5 minutes of arc at the distance it is made for (Webvision: Visual Acuity). We calculate each height as 2 × distance × tan(2.5′ × row ÷ 20).
| Row | Letters | Height on the 10 ft chart | Height on the 20 ft chart |
|---|---|---|---|
| 20/200 (6/60) | 1 | 44.3 mm | 88.7 mm |
| 20/100 (6/30) | 2 | 22.2 mm | 44.3 mm |
| 20/70 (6/21) | 3 | 15.5 mm | 31.0 mm |
| 20/50 (6/15) | 4 | 11.1 mm | 22.2 mm |
| 20/40 (6/12) | 5 | 8.9 mm | 17.7 mm |
| 20/30 (6/9) | 6 | 6.6 mm | 13.3 mm |
| 20/25 (6/7.5) | 7 | 5.5 mm | 11.1 mm |
| 20/20 (6/6) | 8 | 4.4 mm | 8.9 mm |
Heights in millimetres, computed from the formula above. The first row has 1 letter and the last row has 8, as on a standard Snellen chart.
Limits of a Snellen chart
A Snellen chart is quick, but the rows have different numbers of letters and tighter spacing toward the bottom, and some letters are easier than others (EyeWiki: Visual Acuity Testing in Adults). It is a screening aid. If you cannot read the 20/20 row, or your vision seems to have changed, see an eye care professional. You can also try the on-screen eye test or the astigmatism test.
Frequently asked questions
What is a Snellen chart?
A Snellen chart shows rows of letters that get smaller. The American Academy of Ophthalmology’s EyeWiki says it was created by Dutch ophthalmologist Dr. Hermann Snellen in 1862 and is the most widely used chart in clinical practice. Letters sit on a 5 by 5 grid, so their height subtends 5 arcminutes.
What does 20/20 mean on an eye chart?
The Snellen fraction is the testing distance divided by the distance at which the letter subtends 5 arcminutes. With 20/20 you read, at 20 feet, letters that subtend 5 arcminutes there. In meters it is written 6/6. A 20/40 row has letters twice that tall.
What are the limits of a Snellen chart?
EyeWiki notes that the lines have an unequal number of letters, from one letter at 20/200 to eight at 20/20, so spacing gets tighter and crowding can occur, and some letters are easier to read than others. The ETDRS chart was developed to standardize measurement for clinical research.
How far should I stand from the chart?
Stand at the distance printed on the chart. Clinics use 20 feet (6 meters) for Snellen, according to EyeWiki. Our 10-foot chart has letters sized for 10 feet. Measure the distance with a tape measure, and use good, even light with the chart at about eye level.
Sources
- American Academy of Ophthalmology EyeWiki. Visual Acuity Testing in Adults. https://eyewiki.aao.org/Visual_Acuity_Testing_in_Adults
- Kalloniatis M, Luu C. Visual Acuity. Webvision, University of Utah (also on NCBI Bookshelf). https://www.webvision.pitt.edu/book/part-viii-psychophysics-of-vision/visual-acuity/
All sources were read on October 11, 2026. We only state what the sources say, and we do not invent numbers. These pages have not been reviewed by an eye care professional. Spot a mistake? Email info@colorblindcheck.app.