Icon Design: A Practical Guide

Icons look simple but require a surprising amount of system thinking. A well-designed icon set feels effortless and supports the UI; a poorly designed one undermines every screen it appears on. This guide covers the rules that make an icon set cohesive.

The System

DecisionCommon valueNotes
Canvas size24×24Standard; 16/20/32 for variants
Safe area / padding2px each sideKeep shapes within 20×20 inside 24×24
Stroke width1.5px or 2pxOne width across the set
Corner radius2px (small), 4px (medium)Consistent across set
Line caps / joinsRound or square — pick oneMixing looks accidental
StyleOutline, filled, or duotoneOne primary; second as state variant

Rules That Make Sets Cohesive

  1. Same canvas, same safe area — all icons live in identical bounding boxes so they align visually in lines and grids.
  2. Same stroke width — a single decision applied everywhere.
  3. Same corner treatment — round corners or square corners, not both.
  4. Same visual weight — even when icons differ in subject, perceived "darkness" should be similar.
  5. Optical adjustments — center shapes optically, not geometrically.

Common Mistakes

  • Inconsistent stroke widths across the set.
  • Some icons filled to the edge, others with generous padding — they read as different sizes.
  • Detail levels that vary — a phone icon with 10 details next to a simple speech bubble.
  • Pixel-aligned vs sub-pixel — shapes that don't sit on the pixel grid render fuzzy.
  • Using line icons in small sizes without thicker variants — strokes disappear at 16px.

Production Output

  • Export as SVG with cleaned-up paths (no transform attributes, single fill/stroke per path).
  • Strip unused attributes and metadata.
  • Name consistently: category-name-state (e.g., nav-home-filled).
  • Provide both light and dark variants if your stroke/fill colors need to invert.

Try It Yourself

Convert SVG icons to PNG variants for export with DesignKit's converter.

SVG to PNG →

Frequently Asked Questions

A fixed canvas (typically 24×24) with a safe area inside. Shapes designed inside it ensure consistent scale and edges.
Consistency matters more than the choice. Many systems use outline default + filled active.
1.5px or 2px at 24×24. One width across the entire set.
Mathematical center isn't always perceived as centered. Nudge shapes so they look balanced.
16px inline, 20px compact, 24px default, 32px large, 48px+ feature. Design separate optimised versions for very different sizes.