A true-size eye test chart for screen or print
This eye test chart draws the three charts used for visual-acuity screening — the classic Snellen chart, an ETDRS-style LogMAR chart with five letters on every line, and a tumbling E chart for young children and people who do not read the Latin alphabet — at their real size for the distance you choose: 3, 4 or 6 metres, 10 or 20 feet, or any distance you type.
Every optotype is constructed on the standard 5 × 5 grid so that the smallest detail is one-fifth of the letter height, and the 6/6 (20/20) letters subtend exactly 5 minutes of arc at the test distance — 8.73 mm tall at 6 m. You can show one line at a time on a screen you have calibrated with a bank card, or print a vector PDF with a 50 mm check bar to confirm the printer did not scale it. Nothing is uploaded.
It is a screening aid, not an eye examination, and it cannot replace a visit to an optometrist or ophthalmologist.
How to use the Eye Test Chart
- Choose the Chart and the Viewing distance. Measure the distance from the chart to the eyes with a tape measure.
- For the on-screen chart, open Calibrate your screen and drag the slider until the outline matches a bank card held against the screen.
- To print, pick the paper size and press Print chart or Download PDF; print at 100% (“Actual size”) and check that the bar measures 50 mm.
- Light the chart well, stand at the distance, cover one eye with the palm and read from the largest line down. Use the arrow keys or the arrows to change the on-screen line, and New letters to avoid memorising.
- The smallest line read with no more than one or two mistakes is the result for that eye. Repeat with the other eye, with and without glasses.
Eye Test Chart features
Exact letter sizes
Height = 2 × distance × tan(2.5′ × MAR): 8.73 mm for 6/6 at 6 m, 5.82 mm at 4 m, scaled for every line.
Three chart types
Snellen lines from 6/60 to 6/5 (20/200 to 20/16), LogMAR 1.0 to −0.3 in 0.1 steps, and tumbling E with no repeated direction side by side.
Screen calibration
A credit-card outline (ISO/IEC 7810 ID-1, 85.60 mm) gives the true pixels per millimetre for your display; it is remembered on this device.
Printable PDF
Vector letters at true size on A4 or Letter, with line labels, letter heights and a 50 mm scale bar on every page.
Mirror mode
Reverses the letters so you can sit beside the screen and read it in a mirror placed at half the distance — useful in small rooms.
Fresh letters
Sloan-style letters (C D H K N O R S V Z) are shuffled on demand and never repeat within a line.
How the chart sizes are calculated
Visual acuity is defined by angles. A person with “normal” 6/6 (20/20) vision can recognise a letter whose overall height subtends 5 minutes of arc and whose strokes subtend 1 minute. At distance d, the letter height is 2 × d × tan(2.5′), so at 6 m it is 2 × 6000 mm × 0.000727 = 8.73 mm. A 6/12 letter is twice that size, and 6/60 is ten times (87.3 mm).
LogMAR is the logarithm of the minimum angle of resolution: logMAR 0.0 equals 6/6, 0.3 equals 6/12 and 1.0 equals 6/60. Each line is 0.1 log units (about 26%) smaller than the one above, every line has five letters, and the gap between lines equals the height of the next line — the ETDRS layout. On A4 or Letter paper the largest lines are shortened to the letters that fit.
| Metric (6 m) | Imperial (20 ft) | LogMAR | Letter height at 6 m | At 3 m |
|---|---|---|---|---|
| 6/60 | 20/200 | 1.0 | 87.3 mm | 43.6 mm |
| 6/24 | 20/80 | 0.6 | 34.9 mm | 17.5 mm |
| 6/12 | 20/40 | 0.3 | 17.5 mm | 8.73 mm |
| 6/9 | 20/30 | 0.18 | 13.1 mm | 6.55 mm |
| 6/6 | 20/20 | 0.0 | 8.73 mm | 4.36 mm |
Getting a reliable result at home
- Distance matters: a 10% error in distance gives a 10% error in acuity. Measure from the chart to the eyes.
- Lighting: light the chart evenly and avoid glare; screens should be at full brightness with a white background.
- Print scale: if the 50 mm bar measures 48 mm, the printer shrank the page and the results will be about 4% optimistic.
- Children: with the tumbling E, ask the child to point the way the “legs” of the E point; practise on the big line first.
- When to see a professional: if either eye cannot read the 6/12 line, if the two eyes differ by two lines or more, or if you notice any change in your vision. The UK, for example, uses 6/12 as the minimum standard for driving.
Eye Test Chart FAQ
How do I use a printable eye test chart?
Print it at 100% scale, check that the 50 mm bar is 50 mm, fix it at eye level in good light, and stand at the distance printed on the chart. Cover one eye and read down to the smallest line you can; that line’s number is your result.
What size is a 20/20 letter?
At 20 feet (6.1 m) a 20/20 letter is about 8.87 mm tall; at 6 m it is 8.73 mm. It is always the size that subtends 5 minutes of arc at the test distance.
Can I test my eyes on a phone or laptop screen?
Yes, after calibrating with a card, but screens are small: at 3 m the large lines may not fit. The on-screen chart shows as many letters as fit and tells you if a line is too big; a printed chart is better for the top lines.
What is the difference between Snellen and LogMAR?
Snellen charts have a few large letters at the top and many small ones at the bottom, with irregular steps. LogMAR charts have five letters on every line and equal 0.1 log steps, which makes results more precise and repeatable.
Does a good result mean my eyes are healthy?
No. Acuity is only one measure; many eye diseases do not affect it until late. Regular eye examinations are still important, especially for children, people with diabetes and anyone over 40.
Is this eye test chart accurate?
The sizes are computed exactly and the letters follow the 5 × 5 construction, but the letter shapes are Sloan-style approximations, and accuracy depends on calibration, distance and lighting. Treat the result as a screening guide.