Calculators

Magnification

Spectacle, relative distance & electronic

Back vertex powerDFront curveDCentre thicknessmmIndexVertex distancemm

Enter values to calculate

Reference

SM = [1 / (1 − (t/n)F₁)] × [1 / (1 − hF)], h = vertex distance + 3 mm to the entrance pupil.

Relative distance magnification = original ÷ new viewing distance. Aniseikonia becomes symptomatic around 3–5% difference.