What is the ANSI 256-color palette?

It is the standard extended color set most terminals support. Codes 0 to 15 are the system and bright colors, codes 16 to 231 form a 6×6×6 RGB cube, and codes 232 to 255 are a 24-step grayscale ramp. Together they give 256 selectable colors.

How does the tool find the nearest color?

It computes the exact RGB value of all 256 palette entries, then measures the squared Euclidean distance from your hex color to each one and returns the entry with the smallest distance. If the distance is zero, your color is an exact palette match.

How do I use the resulting code in a terminal?

Wrap the code in an escape sequence. For text color use ESC[38;5;Nm and for background use ESC[48;5;Nm, where N is the code. Reset afterwards with ESC[0m. The ESC character is the literal escape byte, often written \e or \033.

How are the cube colors calculated?

For codes 16 to 231 the index minus 16 splits into red, green and blue levels of 0 to 5. Each non-zero level maps to the value 55 plus 40 times the level, while level 0 maps to 0. That non-linear step is why the cube is not a simple even spread.

Why is my color only approximate?

The 256-color palette is a fixed grid, so most arbitrary hex colors fall between palette points. The converter returns the perceptually nearest available code, but for true color you can use a terminal that supports 24-bit ANSI with the ESC[38;2;R;G;Bm sequence instead.

What is the ANSI Color Code Converter?

Free ANSI color code converter. Enter a hex color and get the closest ANSI 256-color terminal code, with ready-to-use foreground and background escape sequences. Searches the full palette — 16 system colors, the 6×6×6 cube and the grayscale ramp — by RGB distance. Runs entirely in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

ANSI Color Code Converter

Name: ANSI Color Code Converter
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

Get one useful tool a week

Like this tool? Enter your email and we'll send you one genuinely useful Gera tool a week — plus a link to come back to this one. No spam, one-click unsubscribe any time.

Map any hex color to the closest terminal color

The ANSI Color Code Converter finds the nearest entry in the ANSI 256-color palette for any hex color and gives you the escape sequences to use it. It is the quick way to translate a brand color or design swatch into something your shell scripts, CLI tools and terminal UIs can actually display.

How it works

The 256-color palette is divided into three distinct regions, each with precise RGB definitions:

Codes 0–15: the 16 fixed system colors — 8 standard (black, red, green, yellow, blue, magenta, cyan, white) and 8 bright variants. These are defined by the terminal, not the spec, so they vary slightly across emulators.
Codes 16–231: a 6×6×6 color cube where index = 16 + 36·r + 6·g + b. Each channel level maps to 0 for level 0 or 55 + 40·level otherwise, giving values 0, 95, 135, 175, 215, 255.
Codes 232–255: a 24-step grayscale ramp where each step value is 8 + 10·(index − 232), running from near-black (code 232) to near-white (code 255).

The converter generates the exact RGB for all 256 codes, then computes the squared Euclidean distance dr² + dg² + db² between your hex color and each palette entry, returning the code with the smallest distance. A distance of zero means an exact palette match.

Example: finding the nearest code for a blue

Enter #2563eb (a common bright blue from Tailwind’s palette). The palette grid does not include this exact value, so the tool scans all 256 entries and returns the cube code with the closest RGB match, showing a swatch comparison so you can judge the difference visually.

To use the returned code in a shell script:

# Foreground (text) color — replace N with the code
printf '\e[38;5;Nm%s\e[0m\n' "hello in your color"

# Background color — use 48 instead of 38
printf '\e[48;5;Nm%s\e[0m\n' "highlighted text"

The \e[0m at the end resets all attributes so subsequent output is not stained with the color.

When to use 24-bit true color instead

If your terminal emulator supports 24-bit “true color” (most modern ones do — check $COLORTERM for truecolor), you can skip the 256-palette entirely and use the exact hex values:

# 24-bit foreground: ESC[38;2;R;G;Bm
printf '\e[38;2;37;99;235mExact blue\e[0m\n'

This is always more accurate than the nearest palette approximation. Use the 256-color codes when you need to support older terminals, SSH sessions to legacy systems, or environments where TERM=xterm-256color but 24-bit support is uncertain.

Common use cases

Styling CLI tool output to match a product’s brand palette
Writing terminal UI components (using curses, blessed, or similar) that need specific colors
Generating colored diff or status output in CI logs
Checking which palette code a terminal theme uses for a given visual color