SGR 48;5;n — 256-color background

Byte forms

Every common string-literal form so you can paste-and-search either direction.

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Description

Background sibling of sgr-fg-256 (\x1b[38;5;Nm). N is 0–255 with identical palette layout — 0–7 the basic 16-color slots (the 40–47 equivalents), 8–15 the bright slots (the 100–107 equivalents), 16–231 a 6×6×6 RGB cube indexed as 16 + 36*r + 6*g + b with each component in 0..5, and 232–255 a 24-step grayscale ramp from near-black to near-white. The colon-form \x1b[48:5:Nm is accepted by ECMA-48-strict parsers alongside the more common semicolon form. The 256-color extension originated in xterm and is documented in xterm-ctlseqs §"256-color support"; it predates the truecolor escape by ~15 years and remains the most portable way to express anything beyond the basic 16.

Terminal support is broader than truecolor but narrower than the 16-color baseline. The Linux console / fbcon refuses 256-color in framebuffer mode (the kernel palette only holds 16 slots), so \x1b[48;5;202m renders as a no-op or fallback color depending on the kernel build — the support matrix above marks it no. Windows conhost.exe supports 256 only since Windows 10 1809; older builds quantize to the nearest 16-color slot. The 16–231 cube is universally available on every other emulator in the matrix; the 232–255 grayscale ramp is where emulators diverge most — alacritty, kitty, wezterm and modern gnome-terminal render an even ramp, while screen 4.x quantizes the dimmer grays to pure black on some builds and 5.0 fixed it. tmux requires set -ag terminal-overrides ',xterm-256color:Tc' (or the modern RGB cap) to forward 256-color escapes intact to the outer terminal; without it \x1b[48;5;202m reaches tmux but never makes it past.

Reset just the background with \x1b[49m — surgical, leaves foreground and other attributes intact. The full reset \x1b[0m clears everything. To convert an arbitrary RGB triplet to the nearest cube index, use 16 + 36*round(r*5/255) + 6*round(g*5/255) + round(b*5/255); for grayscale targets use 232 + round(luma*23/255). If the rendered output looks wrong on a specific terminal, probe $COLORTERM — when it is truecolor or 24bit prefer sgr-bg-truecolor for exact colors; when it is unset or empty but $TERM matches *-256color, the 256-cube is the most portable target.

Spec citation: xterm-ctlseqs (256-color extension)

Examples

printf '\033[48;5;202m highlight \033[49m\n'

print('\x1b[48;5;202m highlight \x1b[0m')

fmt.Print("\x1b[48;5;202m highlight \x1b[0m")

console.log('\x1b[48;5;202m highlight \x1b[0m')

printf("\x1b[48;5;202m highlight \x1b[0m\n");

Terminal support

xterm

yes

Linux console (fbcon)

no

macOS Terminal.app

yes

iTerm2

yes

Windows Terminal

yes

cmd.exe / ConPTY

partial

kitty

yes

alacritty

yes

WezTerm

yes

Ghostty

yes

GNOME Terminal

yes

Konsole

yes

tmux

yes

GNU screen

yes

Related sequences

• SGR 38;5;n — 256-color foreground
• SGR 48;2;R;G;B — 24-bit truecolor background
• SGR 40–47 — Background color (8 basic)

In the family cookbook

↗SGR cookbook · 3. 256-color indexed — `\x1b[38;5;n m`