# Convert 3 digits color to 6 digits color

Double each digit of a #rgb color.

Canonical: https://1loc.dev/misc/convert-3-digits-color-to-6-digits-color/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Local fixtures; no external services
Updated: 2026-10-28

## Implementation

```javascript
function toFullHexColor(color) { return `#${(color.startsWith('#') ? color.slice(1) : color).split('').map(digit => `${digit}${digit}`).join('')}`; }
```

## Input

```json
"#16a"
```

## Expected output

```json
"#1166aa"
```

## Edge case

Input:
```json
"fff"
```
Output:
```json
"#ffffff"
```

## Limits

- Input must be three hexadecimal digits, with or without #.

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-3-digits-color-to-6-digits-color.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.