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What Is the Line Height Calculator?

Calculate optimal line-height values for any font size. Preview text readability with adjustable font, size, and line-height combinations.

Why Use This Tool?

Line height (leading) is one of the most impactful typography settings for readability. Too tight and lines blur together; too loose and the eye loses track between lines. This tool helps you find the sweet spot.

How to Use This Line Height Calculator

  1. Enter your font size — Type the font size you're working with in pixels. Common values: 14–16px for body text, 24–48px for headings.
  2. Choose a ratio — Select a line-height multiplier. The tool suggests optimal ratios based on your font size and content type (body text, headings, captions).
  3. Preview the result — See your text rendered live with the calculated line-height applied. Compare different ratios side by side.
  4. Copy the CSS — Grab the line-height value as a unitless ratio (recommended) or in pixels, rem, or em — ready for your stylesheet.

Tips and Best Practices

Frequently Asked Questions

What's the ideal line-height?
For body text, 1.4 to 1.6 is generally optimal. Headings work well at 1.1 to 1.3. The ideal value depends on font size, line length, and the specific typeface.
Should I use unitless or px line-height?
Always use unitless values (line-height: 1.5) rather than fixed units (line-height: 24px). Unitless values scale proportionally when font-size changes, while fixed values don't.
How does line-height interact with line length?
Longer lines need more line-height to help the eye track back to the start of the next line. Short lines (like mobile viewports) can use tighter leading.
What is a good line-height for body text?+
For body text at 14–18px, a line-height of 1.5 to 1.7 is generally optimal. WCAG 2.1 Success Criterion 1.4.12 recommends at least 1.5× the font size for paragraph text to ensure readability.
Should I use px, em, or unitless line-height?+
Unitless values are recommended (e.g., line-height: 1.6). Unlike px or em, unitless values scale proportionally when the font size changes — avoiding inheritance problems where child elements get an unexpected fixed line-height.
How does line-height affect accessibility?+
Adequate line-height improves readability for people with dyslexia, low vision, and cognitive disabilities. WCAG recommends at least 1.5× for body text. Users should also be able to override line-height to at least 2× without breaking the layout.

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Related Article How to Calculate Optimal Line Height for Typography →

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