Calculadora de Lente Delgada
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
1/f = 1/d_o + 1/d_i
About this calculator
The Thin Lens Calculator solves the Gaussian lens equation (1/f = 1/do + 1/di) for converging and diverging lenses. It calculates the focal length, object distance, or image distance given the other two values. The tool also determines the linear magnification (M = -di/do) and indicates whether the image is real or virtual, upright or inverted, and whether the object is beyond or before the focal point.
The operation is based on the thin lens formula, which relates the focal length (f) to the object distance (do) and image distance (di). For converging lenses, f is positive; for diverging lenses, f is negative. The calculator uses the equation to find the missing term and then computes the magnification. The sign of di indicates whether the image is real (positive di) or virtual (negative di). The sign of M indicates whether the image is inverted (negative M) or upright (positive M).
This calculator is useful in optics labs, lens design projects, and for physics students verifying image formation experiments. For example, when designing a magnifying glass or a camera lens system, knowing the image position and size is essential. It is also used in ophthalmology to calculate eyeglass lens corrections.
Cautions: The formula assumes thin lenses (negligible thickness) and paraxial rays (small angles). For thick lenses or large apertures, results may be inaccurate. Additionally, the calculator does not account for chromatic or spherical aberrations. Ensure you use consistent units (usually centimeters or meters) and that the entered values are realistic for the lens type.
Frequently asked questions
What does a negative focal length mean?
A negative focal length indicates a diverging (concave) lens. Diverging lenses spread light rays and form virtual images.
How do I know if the image is real or virtual?
The image is real if the image distance (di) is positive, and virtual if di is negative. Real images can be projected onto a screen; virtual ones cannot.
What is linear magnification and how to interpret it?
Linear magnification (M) is the ratio of image height to object height. If M is negative, the image is inverted; if positive, it is upright. The absolute value indicates the magnification factor.
Does this calculator work for thick lenses?
No, the thin lens formula assumes negligible thickness. For thick lenses, use the thick lens formula or ray matrices.
What units should I use?
Use the same unit for all distances (e.g., centimeters or meters). The calculator does not automatically convert units.