---
title: "Thin Lens Equation calculator — AperiOptic"
description: "Image distance & magnification from object distance and focal length. Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/thin-lens-equation"
---

# Thin Lens Equation calculator

Image distance & magnification from object distance and focal length.

Category: [Geometric Optics](https://aperioptic.com/calculators)

Formula: `1/f = 1/do + 1/di · m = -di/do`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| Focal length | `f` | mm | 50 |
| Object dist | `do` | mm | 200 |

## Result with the default inputs

- Image dist: 66.6667 mm
- Magnification: -0.3333×

Open it with your own values: put each input in the address as a parameter, for example [`/calculators/thin-lens-equation?f=50`](https://aperioptic.com/calculators/thin-lens-equation?f=50). A unit other than the listed one goes in `<parameter>_unit`.

Read more: [Wikipedia: Thin lens](https://en.wikipedia.org/wiki/Thin_lens)

[All optics calculators](https://aperioptic.com/calculators)

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The interactive page: https://aperioptic.com/calculators/thin-lens-equation (AperiOptic runs in the browser; free, no account). Every page of the site as Markdown: https://aperioptic.com/llms.txt