Lens Maker's Equation Calculator
Compute focal length from refractive index and surface radii (1/f = (n−1)(1/R₁−1/R₂)).
Input Data
Lens refractive index n.
First surface radius R₁.
m
Second surface radius R₂.
m
Lens thickness (thin-lens approx).
m
Results
f in cm.
25cm
P = 1/f (m).
4D (1/m)
1/f.
41/m
At a glance:1/f = (n−1)(1/R₁ − 1/R₂) (thin lens). Complements lens-formula and lens-power.
Formula
1/f = (n−1)(1/R₁ − 1/R₂).
How to Use
- Enter n and the two radii.
- The tool returns f and power.
Case Studies
n=1.5, R₁=0.1, R₂=−0.1
f = 0.1 m (10 cm), P=10 D.
FAQ
Sign of radii?
Convex surface positive, concave negative (per convention).
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.