Author name: Ruby Midwest

Optical Kerning vs Metric Kerning: A Complete Guide for Designers If you have ever opened InDesign, Illustrator, or Figma and wondered whether to choose optical kerning or metric kerning, you are not alone. This is one of the most common typographic decisions designers face, and the wrong choice can make beautifully crafted layouts look subtly off. In this guide, we break down exactly how optical kerning and metric kerning work, when each option produces better results, and how to decide which one to use for headlines, body text, and logo projects. What Is Kerning, and Why Does It Matter? Kerning is the adjustment of space between individual letter pairs. Unlike tracking, which adjusts spacing uniformly across a range of characters, kerning targets specific pairs like AV, To, or WA where the default spacing can look uneven to the human eye. Good kerning makes text feel balanced and readable. Poor kerning creates awkward gaps or collisions that distract readers, even if they cannot consciously identify the problem. Most professional design applications give you two automatic kerning methods to choose from: metric and optical. Understanding the difference between them is essential for any serious design work. What Is Metric Kerning? Metric kerning (sometimes called “metrics” in software menus) uses the kerning tables built into the font file by the typeface designer. When a font is created, the designer carefully defines spacing values for hundreds or even thousands of specific letter pairs. These values are stored inside the font as metadata. When you select metric kerning in your design software, the application reads those built-in pair values and applies them automatically. Strengths of Metric Kerning Reflects the original intent of the type designer, who spent considerable time fine-tuning letter pair relationships. Produces highly consistent results across long blocks of text. Works exceptionally well with professional, well-crafted fonts that include extensive kerning tables. Generally the default setting in most design applications for good reason. Weaknesses of Metric Kerning Only as good as the kerning data in the font. Budget or free fonts often have incomplete or missing kerning tables. Cannot adapt when you mix different typefaces in the same line of text. May produce looser spacing than desired at large display sizes. What Is Optical Kerning? Optical kerning ignores the font’s built-in kerning tables entirely. Instead, the design software analyzes the actual shapes of adjacent characters and calculates spacing on the fly based on their outlines. The algorithm tries to create visually even spacing by looking at the geometry of each letter pair. Strengths of Optical Kerning Works well with fonts that have poor or missing kerning tables. Produces good results when mixing two or more different typefaces on the same line. Can deliver tighter, more visually balanced spacing at large display sizes. Useful as a starting point before manual kerning adjustments. Weaknesses of Optical Kerning Ignores the carefully crafted decisions of the original type designer. May produce inconsistent results in long passages of body text. The algorithm is not perfect and can sometimes over-correct or under-correct specific pairs. Can slow down performance in very long documents because spacing is calculated in real time. Optical Kerning vs Metric Kerning: Side-by-Side Comparison Feature Metric Kerning Optical Kerning Data source Built-in font kerning tables Algorithm analyzes character shapes Best for body text Yes (with quality fonts) Only if font has poor kerning data Best for headlines Sometimes too loose Often tighter and more balanced Mixed typefaces Poor (tables don’t cover cross-font pairs) Good (shape-based calculation adapts) Logo and display work Starting point, then manual adjustments Better starting point for manual refinement Free/budget fonts Often produces poor results Usually better than metrics in this case Performance Fast (reads stored values) Slightly slower (real-time calculation) When to Use Metric Kerning Metric kerning should be your default choice for body text when you are working with professional, well-made typefaces. Foundries like Adobe, Monotype, and independent type designers invest significant effort into their kerning tables, and using metrics honors that work. Ideal scenarios for metric kerning: Long-form body text in books, magazines, reports, and websites where consistency across thousands of words is critical. Professional fonts from reputable foundries that you know include thorough kerning data. Tabular data and numbers where consistent spacing ensures columns align properly. Templates and brand guidelines where reproducibility matters across different team members and machines. When to Use Optical Kerning Optical kerning shines in situations where the built-in font data either does not exist, is incomplete, or simply does not apply. Ideal scenarios for optical kerning: Headlines and display text set at large sizes where even minor spacing inconsistencies become very visible. Free or budget fonts that lack comprehensive kerning tables. Mixing typefaces on the same line, such as pairing a serif with a sans-serif in a headline. Decorative or script fonts where the built-in metrics may not account for all stylistic variations. Logo design as a starting point before you apply manual kerning adjustments. Practical Workflow: Headlines, Body Text, and Logos Body Text For paragraphs and running text, start with metric kerning. If you notice uneven spacing (which can happen with lower-quality fonts), switch to optical and compare. In most cases with a professional typeface, metrics will look better because the type designer optimized pair values for reading sizes. Headlines and Titles Large text magnifies every spacing flaw. Try optical kerning first for headlines, then compare with metrics. Optical kerning tends to produce tighter, more visually appealing spacing at display sizes. After selecting your preferred automatic method, manually adjust any pairs that still look off. Common trouble pairs include AV, To, LT, Yo, and WA. Logo and Wordmark Design Neither automatic method is sufficient on its own for logo work. Use optical kerning as your starting point because it adapts to the specific letterforms, then manually kern every single pair. Logo typography demands pixel-perfect spacing, and no algorithm can replace a trained eye at this level of detail. Mixed Typeface Settings Whenever you combine two different fonts on the same line, metric kerning cannot