Thin Lens Equation Calculator

Solve the thin lens equation 1/f = 1/d₀ + 1/dᵢ. Enter any two values to find the third, plus magnification and image type.

Thin Lens Equation Calculator

Solve 1/f = 1/d₀ + 1/dᵢ. Select what to solve for, enter the two known values, and get the result instantly.

Positive = converging; negative = diverging

Distance from object to lens

Positive = real image (opposite side)

Formula

1/f = 1/d₀ + 1/dᵢ

Focal Length (f): 20 cm

Object Distance (d₀): 30 cm

Image Distance (dᵢ): 60 cm

Magnification (m): -2

Real ImageInvertedEnlarged

Key formulas: 1/f = 1/d₀ + 1/dᵢ  |  m = −dᵢ / d₀

Converging lens: f > 0  |  Diverging lens: f < 0  |  Real image: dᵢ > 0  |  Virtual image: dᵢ < 0

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Added Sep 26, 2026

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