How to Convert Prescription to 20/20: Diopter Chart for Men’s Glasses
To convert prescription to 20/20, match your diopter (SPH) value to Snellen equivalents using this chart: 0.00D = 20/20; -1.00D or +1.00D ≈ 20/30; -2.00D or +2.00D ≈ 20/50–20/100. Online calculators simplify this by inputting SPH/CYL/ADD …