Box Drawing & Block Elements Blocks

Before graphical user interfaces became ubiquitous, software developers built entire visual environments using nothing but text characters. The Box Drawing block (U+2500–U+257F) and Block Elements block (U+2580–U+259F) are the Unicode heirs to this tradition — a repertoire of characters that let you draw lines, borders, tables, and filled areas entirely in text. They remain deeply practical today in terminal applications, command-line interfaces, and any context where a monospace font is used.

Box Drawing Characters (U+2500–U+257F)

The Box Drawing block contains 128 characters covering every combination of line segments at the four cardinal directions (left, right, up, down), in both single and double line weights, with various join styles.

Basic Single Lines

The simplest box drawing characters are straight lines:

Corners

Corners join horizontal and vertical lines:

T-Junctions and Crosses

Where three or four lines meet:

Mixed Single/Double Lines

The block includes characters for mixing single and double lines, allowing visual hierarchy in TUI tables:

Building a TUI Border

Using box drawing characters, a terminal application can draw a bordered panel:

╔══════════════════╗
║  Unicode FYI     ║
╠══════════════════╣
║ Characters: 149K ║
║ Blocks: 167      ║
╚══════════════════╝

This structure uses: - ╔ U+2554, ═ U+2550, ╗ U+2557 for the top border - ║ U+2551 for vertical sides - ╠ U+2560, ╣ U+2563 for the horizontal divider - ╚ U+255A, ╝ U+255D for the bottom border

Popular terminal UI libraries like Python's rich, Go's tview, and Rust's tui-rs all use these characters internally.

Dashed and Dotted Lines

The box drawing block also includes dashed variants for visual variety:

Block Elements (U+2580–U+259F)

The Block Elements block contains 32 characters that divide a character cell into filled and empty regions. Because each character cell in a monospace font is a fixed rectangular grid, these characters can create smooth-looking gradients, progress bars, and pixel art by selectively filling halves, quarters, and eighths of each cell.

Half Block Characters

Shade Characters

The three shade characters are among the most visually recognizable box/block characters:

These create a four-step grayscale ramp used for shadows, gradients, and the classic "installing..." progress visualization of early DOS software. In modern terminals with color support, these shade characters can be colored to create smooth-looking gradients.

Vertical Eighths for Progress Bars

A particularly useful subset is the vertical eighths, which fill the cell from the bottom up in eight steps:

These eight characters make it possible to render a smooth bar chart or histogram in a terminal with 8× the vertical resolution of a simple block character approach. Python's sparklines libraries, btop, and many other TUI tools use exactly this technique.

Retro Computing Aesthetics

Box drawing characters carry a strong retro-computing aesthetic associated with the era of DOS, BBS (Bulletin Board Systems), and early Unix terminals. ANSI art — the BBS-era art form of creating elaborate images using box drawing, block elements, and ANSI color codes — still has an active community today.

Many modern developer tools intentionally evoke this aesthetic: - htop / btop for system monitoring - git log --graph for commit history - Database query results in psql and mysql clients - Python's rich library for terminal output formatting

Font Support and Alignment

Box drawing characters only work correctly when: 1. A monospace font is used 2. The font includes all the box drawing characters 3. Line spacing is tight enough that characters in adjacent rows visually connect

Popular monospace fonts with excellent box drawing support include Fira Code, JetBrains Mono, Cascadia Code, and Iosevka. If a font lacks some of the mixed single/double or heavy variants, rendering will be inconsistent.

The recommendation for terminal application developers is to test on multiple fonts and provide ASCII fallbacks (-, |, +) for environments where box drawing characters may not render correctly.