Lensmaker's Equation

1/f = (n - 1)·(1/R1 - 1/R2) => f = 1 / ((n - 1)·(1/R1 - 1/R2))

What it says

Gives the focal length of a thin lens from its refractive index and the radii of curvature of its two surfaces.

Symbol	Quantity	Dimension
`n`	Refractive index (dimensionless)	`1`
`R1`	Radius of curvature, front surface (m)	`L`
`R2`	Radius of curvature, back surface (m)	`L`
`f`	Focal length (m)	`L`

Enter what you know. No account needed.

n — Refractive index (dimensionless)R1 — Radius of curvature, front surface (m)R2 — Radius of curvature, back surface (m)