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.

Americanized Real World Acuity Chart

	1"	2"	3"	4"	5"	6"	8"	10"	12"
20/15	43'	86'	129'	172'	215'	258'	344'	430'	516'
20/20	57'	115'	172'	229'	286'	344'	458'	573'	688'
20/25	72'	143'	215'	286'	358'	430'	573'	716'	859'
20/30	86'	172'	258'	344'	430'	516'	688'	859'	1031'
20/40	115'	229'	344'	458'	573'	688'	917'	1146'	1375'
20/50	143'	286'	430'	573'	716'	859'	1146'	1432'	1719'

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:

Metric Real World Acuity Chart

	25mm	50mm	75mm	100mm	125mm	150mm	200mm	250mm	300mm
6/5 (20/15)	14m	29m	43m	57m	72m	86m	115m	143m	172m
6/6 (20/20)	17m	34m	52m	69m	86m	103m	138m	172m	206m
6/9 (20/30)	26m	52m	77m	103m	129m	155m	206m	258m	309m
6/12 (20/40)	34m	69m	103m	138m	172m	206m	275m	344m	413m
6/15 (20/50)	43m	86m	129m	172m	215m	258m	344m	430m	516m

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)