# Convert Fahrenheit to Celsius

Subtract 32 and multiply by 5/9.

Canonical: https://1loc.dev/misc/convert-fahrenheit-to-celsius/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Local fixtures; no external services
Updated: 2026-10-28

## Implementation

```javascript
function fahrenheitToCelsius(fahrenheit) { return (fahrenheit - 32) * 5 / 9; }
```

## Input

```json
68
```

## Expected output

```json
20
```

## Edge case

Input:
```json
-40
```
Output:
```json
-40
```

## Limits

- The inverse of Convert Celsius to Fahrenheit; results are not rounded.

The lab validates types and size before calling this function. Add equivalent validation at your own trust boundary.

## Source and license

Original: https://github.com/phuocng/1loc/blob/14b481cf60dff1620ab1bb99a43b1f68068cdd9b/contents/convert-fahrenheit-to-celsius.mdx
Source file (this edition): https://github.com/akamind/1loc/blob/0a77f131b22d2ba3b7ec1728846f900c22821678/contents/convert-fahrenheit-to-celsius.mdx
Author: Nguyen Huu Phuoc and original contributors
Contributors: See original repository history
Source commit: 14b481cf60dff1620ab1bb99a43b1f68068cdd9b
Copyright (c) 2020 phuoc-ng
License: MIT — https://1loc.dev/licenses/
Maintainer: Oveyon
Modifications: Curated implementation; explicit input contract, edge case and limits. Original MDX retained as inert source evidence.