Quick Reference: Real World Acuity Guide
There is a formula to discover what the acuity equivalent of any sized text is from a given distance, but for those who are a little busy juggling everything else in life and trying to work EndMyopia onto an already full plate, here is another tool for you. This real world acuity reference chart is designed to help you make the most of your EM walks by understanding what different size texts you can expect to see from various distances.
| 1" | 2" | 3" | 4" | 5" | 6" | 8" | 10" | 12" | |
| 20/15 | 76' | 153' | 229' | 306' | 386' | 458' | 611' | 764' | 917' |
| 20/20 | 57' | 115' | 172' | 229' | 286' | 344' | 458' | 573' | 688' |
| 20/25 | 46' | 92' | 138' | 183' | 229' | 275' | 367' | 458' | 550' |
| 20/30 | 38' | 76' | 115' | 153' | 191' | 229' | 306' | 382' | 458' |
| 20/40 | 29' | 57' | 86' | 115' | 143' | 172' | 229' | 286' | 344' |
| 20/50 | 23' | 46' | 69' | 92' | 115' | 138' | 183' | 229' | 275' |
Please note: you will see text size across the top notated as a number followed by " to indicate inches, and within the chart a number followed by ' to indicate feet from target.
Furthermore understand that this assumes good natural light. Lower light will require an adjustment in expectation as light plays a very important role in vision.
And for those of you who use the Metric System:
| 25mm | 50mm | 75mm | 100mm | 125mm | 150mm | 200mm | 250mm | 300mm | |
| 6/5 (20/15) | 21m | 41m | 62m | 83m | 103m | 124m | 165m | 206m | 248m |
| 6/6 (20/20) | 17m | 34m | 52m | 69m | 86m | 103m | 138m | 172m | 206m |
| 6/9 (20/30) | 11m | 23m | 34m | 46m | 57m | 69m | 92m | 115m | 138m |
| 6/12 (20/40) | 9m | 17m | 26m | 34m | 43m | 52m | 69m | 86m | 103m |
| 6/15 (20/50) | 7m | 14m | 21m | 28m | 34m | 41m | 55m | 69m | 83m |
For those interested: The formula for getting the distance in feet, and having the font height in inch:
Distance[feet] = (20 * letter size[inch]) / (0.01745 * row number)
And for those of you who use the Metric System: same formula with meter for distance and mm for font height:
Distance[meter] = (6 * letter size[mm]) / (1.45444 * row number)