CSS Grid vs Flexbox

When should we use each method? Here's a simple comparison with visual examples and common use cases for responsive design.

Summary

• Use CSS Grid for two-dimensional layouts (rows AND columns)
• Use Flexbox for one-dimensional layouts (either rows OR columns)
• Grid excels at page-level layouts and complex component structures
• Flexbox is perfect for component-level alignment and distribution

Quick Decision Guide

Choose CSS Grid when:

• You need to control both rows and columns simultaneously
• Creating overall page layouts
• Working with complex, non-linear arrangements
• You want items to align to a strict grid system

Choose Flexbox when:

• You're working in one dimension (horizontal or vertical)
• Centering content or distributing space
• Creating navigation bars, toolbars, or button groups
• You need flexible item sizing based on content

CSS Grid: Two-Dimensional Power

Best Use Cases

Grid shines when you need precise control over both horizontal and vertical positioning.

1. Page Layouts

.page-layout {
  display: grid;
  grid-template-areas: 
    "header header header"
    "sidebar main aside"
    "footer footer footer";
  grid-template-columns: 200px 1fr 200px;
  grid-template-rows: auto 1fr auto;
  min-height: 100vh;
}

.header { grid-area: header; }
.sidebar { grid-area: sidebar; }
.main { grid-area: main; }
.aside { grid-area: aside; }
.footer { grid-area: footer; }

This creates a classic three-column layout with header and footer that's impossible to achieve cleanly with Flexbox alone.

2. Card Grids

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1rem;
}

Perfect for responsive card layouts where items maintain consistent sizing and automatically wrap to new rows.

3. Complex Forms

.form-grid {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 1rem;
  align-items: center;
}

.full-width {
  grid-column: 1 / -1;
}

Grid makes it easy to create forms where labels and inputs align properly, with some fields spanning multiple columns.

Grid Advantages

• Precise positioning: Place items exactly where you want them
• Overlap capabilities: Items can overlap using z-index
• Responsive by default: auto-fit and minmax() create fluid layouts
• Gap property: Built-in spacing between grid items
• Fraction units (fr): Distribute available space proportionally

Flexbox: One-Dimensional Flexibility

Best Use Cases

Flexbox excels at distributing items along a single axis with flexible sizing.

1. Navigation Bars

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
}

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

Perfect for horizontal navigation with logo on left, links in center, and user menu on right.

2. Centering Content

.center-everything {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

The classic "center a div" solution that actually works reliably.

3. Button Groups

.button-group {
  display: flex;
  gap: 0.5rem;
}

.button-group button {
  flex: 1; /* Equal width buttons */
}

Distribute buttons evenly or let them size based on content.

4. Media Objects

.media-object {
  display: flex;
  gap: 1rem;
}

.media-object__image {
  flex-shrink: 0; /* Don't shrink the image */
}

.media-object__content {
  flex: 1; /* Take remaining space */
}

Classic pattern for avatar + text content where text wraps but image stays fixed.

Flexbox Advantages

• Content-based sizing: Items can grow/shrink based on content
• Alignment control: Precise control over how items align
• Direction flexibility: Easily switch between row and column layouts
• Order property: Reorder items without changing HTML
• Wrapping: Items can wrap to new lines automatically

Common Patterns and Examples

Pattern 1: Grid for Layout, Flex for Components

/* Grid for overall page structure */
.app {
  display: grid;
  grid-template-areas: 
    "header"
    "main"
    "footer";
  grid-template-rows: auto 1fr auto;
  min-height: 100vh;
}

/* Flexbox for header component */
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
}

Pattern 2: Grid for Cards, Flex for Card Content

/* Grid container for cards */
.articles {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
}

/* Flex layout within each card */
.article-card {
  display: flex;
  flex-direction: column;
}

.article-card__content {
  flex: 1; /* Push footer to bottom */
}

Pattern 3: Responsive Navigation

.main-nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
}

@media (max-width: 768px) {
  .main-nav {
    flex-direction: column;
    gap: 1rem;
  }
}

Performance Considerations

CSS Grid:

• Slightly more complex calculations
• Better for static layouts
• Excellent browser support (IE 11+ with prefixes)

Flexbox:

• Generally faster rendering
• Better for dynamic content
• Excellent browser support (IE 10+)

Debugging Tips

Grid debugging:

• Use Firefox DevTools grid inspector
• Add outline: 1px solid red; to visualize grid areas
• Use grid-template-areas for clearer code

Flexbox debugging:

• Check flex-direction and flex-wrap first
• Remember align-items vs justify-content
• Use flex: 1 instead of flex-grow: 1 for consistency

Real-World Decision Framework

Ask yourself:

1. Am I working in one dimension or two?

- One -> Flexbox

- Two -> Grid

2. Do I need items to line up in rows AND columns?

- Yes -> Grid

- No -> Flexbox

3. Is this a page layout or component layout?

- Page -> Grid

- Component -> Flexbox (usually)

4. Do I know the exact size/position I want?

- Yes -> Grid

- No, let content decide -> Flexbox

Conclusion

Both CSS Grid and Flexbox are powerful layout tools that complement each other. Grid excels at two-dimensional layouts and precise positioning, while Flexbox is perfect for one-dimensional layouts and flexible content distribution. The best modern websites use both: Grid for overall page structure and Flexbox for component-level layouts.

Start with the dimension question: one or two? Then consider whether you need precise positioning (Grid) or flexible distribution (Flexbox). With practice, choosing between them becomes intuitive.