Work out visual acuity conversion instantly with clear inputs, formula shown and shareable results.
Converts a Snellen fraction into logMAR and decimal acuity, and restates it in both imperial and metric notation.
Acuity conversion
logMAR = log10(denominator / reference distance); decimal acuity = reference / denominator; 20/20 = 6/6 = logMAR 0.00 = decimal 1.0
Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
logMAR steps are equal in size, so change can be averaged and analysed statistically, unlike Snellen fractions.
Definitions vary, but 1.0 logMAR (6/60 or 20/200) is the common threshold in many jurisdictions.