📐 Justify Text Tool

What is the Justify Text Tool?

Full justification means a block of text is flush on both the left and right edges, with no ragged right margin. In print or in a word processor this is done by stretching the spaces, and sometimes the letters themselves, until each line reaches the margin exactly. In a plain-text or monospace setting, where every character occupies the same width, you cannot stretch a space by half a pixel, so justification instead works by inserting whole extra space characters between words until each line hits the target character count exactly.

The method here has two stages. First a greedy line fill packs words onto a line one at a time, adding a word only while it still fits within the width, counting one space between neighbours. When the next word would overflow, the current line is closed and the word starts a new line. Second, for every line except the last of each paragraph, the gaps between words are widened: the tool works out how many extra spaces are needed, divides them as evenly as possible across the gaps, and gives the leftmost gaps one extra space when the division is not exact. The last line is left alone, because stretching a short final line looks wrong, the same convention typesetters follow.

This greedy approach is fast and predictable, and it is exactly what fixed-width contexts expect: aligned columns in a README, comment blocks in source code, ASCII layouts, or any place a monospace font guarantees that a given number of characters always occupies the same horizontal space. It is not the line-breaking algorithm used by professional typesetting systems such as TeX, which use the Knuth-Plass algorithm to look ahead across a whole paragraph and minimise overall raggedness. For character-grid text the simpler greedy result is clean, fast, and easy to reason about line by line.

This is also a different mechanism from the text-align: justify property in CSS or the justify button in a word processor. Those tools work with proportional fonts and can stretch, or in some renderers compress, the width of spaces by fractions of a pixel, and modern browsers can add tiny amounts of letter-spacing to smooth the result further. None of that applies to plain text: a text file has no font metrics, so the only lever available is whole space characters, which is exactly what this tool manipulates.

Justified prose is also a readability trade-off worth knowing about. The Web Content Accessibility Guidelines (WCAG 1.4.8) advise against fully justifying large blocks of body text, because uneven word spacing can create vertical rivers of white space that some readers, including people with dyslexia or low vision, find harder to track across a line. That guidance is aimed at paragraphs meant to be read for content, such as articles or blog posts. It does not apply to the technical, fixed-width use case this tool targets: code comments, ASCII layouts, and monospace documents, where a uniform character grid is the point, not a stylistic choice.

Several long-standing plain-text conventions rely on exactly this kind of fixed-width formatting: RFC documents traditionally wrap at 72 or 78 characters, PEP 8 recommends a 79-character line limit for Python source, and the classic Git commit message convention wraps the body at 72 characters so it displays cleanly in any terminal. Justifying to one of these widths gives old-style plain text the same clean, flush-edged block shape you would get from a typeset column, without needing a font at all.

When to use it

• Formatting code comment blocks or docstrings to a consistent 60, 72, or 80 column width.
• Laying out plain-text README, changelog, or email signature blocks so both margins line up.
• Preparing ASCII or monospace layouts, such as terminal banners, where every line must reach the same character width.
• Reflowing pasted prose into a tidy fixed-width block for a terminal, config file, or forum post that uses a monospace font.
• Wrapping and justifying Git commit message bodies or RFC-style plain text documents to the traditional 72-column convention.
• Formatting plain-text licence notices, legal disclaimers, or typewriter-style letters that need a clean flush right margin.

How to use the Justify Text Tool

1. Paste or type your text into the input box.
2. Set the line width in characters (for example 60, 72, or 80).
3. Optionally choose whether to stretch the last line of each paragraph and whether to keep blank lines between paragraphs.
4. Read the justified, monospace result and click Copy to use it anywhere that displays text in a fixed-width font.

Formula & method

Worked examples

Common fixed-width line lengths and where they are used

How "ToolNimba makes free tools" justifies at different widths

Text alignment types compared

Common mistakes to avoid

• Expecting it to work in a proportional font. Character-count justification only lines up visually in a monospace (fixed-width) font, where every character is the same width. Pasted into a normal proportional font, the right edge will look ragged again because spaces and letters have different widths.
• Setting the width narrower than your longest word. If a single word is longer than the line width, it cannot be split (this tool does not hyphenate), so that word sits on its own line and overflows the target width. Raise the width or break the word yourself.
• Wanting the last line stretched by default. Like proper typesetting, the last line of each paragraph is left with single spaces, because a stretched final line looks odd. If you genuinely need every line padded, turn on the option to justify the last line too.
• Confusing justify with centre or right align. Justify makes both edges flush by widening the gaps between words. Centring or right-aligning instead adds padding only on one or both ends and leaves the word spacing untouched.
• Justifying long prose meant to be read on screen. Fully justifying multi-paragraph body text can create uneven rivers of white space that make lines harder to track, which is why accessibility guidance such as WCAG 1.4.8 advises against it for general reading content. Save this tool for fixed-width, technical text and keep prose left-aligned.
• Not accounting for tabs or wide Unicode characters. The tool counts characters, but a tab does not always occupy one column, and some Unicode characters, such as emoji or East Asian characters, are visually wider than one monospace column even though they count as one or two characters. Replace tabs with spaces first for predictable, aligned output.

Glossary

Justify (full justification)

Text aligned flush to both the left and right margins, achieved by adjusting the space between words.

Monospace font

A typeface where every character occupies the same horizontal width, so character counts map directly to visual width.

Greedy line fill

A line-breaking method that puts as many words as possible on each line before moving to the next, deciding one line at a time.

Gap

The space between two adjacent words on a line. Extra spaces for justification are added into the gaps.

Ragged right

Left-aligned text where line ends do not reach a common right margin, the opposite of a justified right edge.

River (typography)

A distracting vertical band of white space that appears when several stretched gaps line up down a justified paragraph, most visible with wide word spacing.

CSS text-align: justify

A browser stylesheet property that stretches proportional-font spacing to flush both margins by adjusting rendered font metrics, unlike the plain character-count method this tool uses.

Knuth-Plass algorithm

The line-breaking method used by TeX and many professional typesetters, which looks ahead across a whole paragraph to minimise raggedness, unlike the greedy line-by-line approach used here.

Frequently asked questions