Optics Δ — Lens & Refraction Calculator

All-in-one optics calculator: thin lens, magnification, refractive index, Snell’s law, optical power and critical angle.

Select a formula, choose units, enter values and press “Calculate”.

Distances support mm / cm / m. Angles support degrees / radians. Speed supports m/s and km/s. Standard SI system is used internally.

About Optics Δ

Optics Δ is a powerful online tool for lens and refraction calculations based on fundamental physics formulas. It allows you to calculate focal length, magnification, refractive index, angles of refraction, optical power and critical angle. Dynamic unit switching (mm/cm/m, degrees/radians, m/s/km/s) makes the calculations fast and convenient.

What You Can Calculate

  • Thin lens: 1/f = 1/do + 1/di
  • Magnification: M = −di / do
  • Refractive index: n = c / v
  • Snell’s law: n₁·sinθ₁ = n₂·sinθ₂
  • Optical power: D = 1 / f
  • Critical angle: sinθc = n₂ / n₁

Uses standard SI units internally. Based on classical geometric optics for education and engineering.

SEO Description

Online optics calculator: lens equations, refractive index, Snell’s law, magnification, optical power and critical angle. Unit switching for mm, cm, m, degrees and radians. Fast and free physics tool by DELTOOLLAB.

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