Optical Power of Lens Calculator: Lens Strength ...
Calculate the optical power of a lens or combined lens system in diopters. Understand how convex and concave lenses combine and what your eyeglass prescription me...
What is Optical Power?
Optical power (P) measures how strongly a lens converges or diverges light. It is the reciprocal of focal length in meters. Measured in diopters (D): positive diopters = converging (convex) lens; negative = diverging (concave). Your eyeglass prescription is written in diopters.
👓 Optical Power Calculator
Free calculator for instant results.
📐 Formula
P = 1/f (diopters)
f = focal length in meters. Combined lenses: P_total = P₁ + P₂ + ... (in contact). Thin lens maker equation: P = (n−1)(1/R₁ − 1/R₂).
📝 Worked Example
Convex lens: f = 25 cm = 0.25 m → P = 1/0.25 = +4.0 D
Concave lens: f = −50 cm → P = −2.0 D
Combined in contact: P_total = 4.0 + (−2.0) = +2.0 D
📝 How to Use
❓ FAQ
What do +3.0 D glasses correct?
Farsightedness (hyperopia) — the eye's natural lens is too weak. Adding +3 D converging power brings distant light to focus on the retina.
What is astigmatism?
Different curvatures in different meridians of the cornea. Corrected with cylindrical lenses, specified by cylinder and axis in the prescription.
Veer Kumavat
Founder & AuthorVeer is a 14-year-old student from Nashik, Maharashtra, who built SciFi Calculators to help students worldwide master STEM subjects. He is passionate about making complex science and math problems accessible through intuitive digital tools.