Visual acuity conversion (Snellen, decimal, logMAR)
Converts visual acuity between Snellen feet (20/x), Snellen meters (6/x), decimal acuity, logMAR and MAR.
Inputs
1 of 2Entered as
When to use
- Recording acuity in a different notation, or averaging acuities (average in logMAR, not Snellen).
Pearls and pitfalls
- Each 0.1 logMAR is one ETDRS line (5 letters).
- Count fingers and hand motion have no exact Snellen equivalent; conventions vary.
Why use
All common notations at once with the arithmetic shown.
MAR = Snellen denominator ÷ numerator; decimal = 1 ÷ MAR; logMAR = log₁₀(MAR)