CSS Grid vs Flexbox - When to Use Each

Modern CSS layouts are primarily built using two powerful systems: CSS Grid and Flexbox. Understanding when to use each can dramatically improve your development workflow and the quality of your layouts.

Understanding the Fundamental Difference

The core distinction between these layout systems is dimensional:

• Flexbox is one-dimensional, dealing with either rows OR columns
• CSS Grid is two-dimensional, handling rows AND columns simultaneously

This fundamental difference should guide your choice between the two systems.

When to Use Flexbox

Flexbox excels at these scenarios:

1. Navigation Menus and Toolbars

For horizontal navigation bars where items need to be evenly spaced or aligned:

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

2. Centering Elements

The classic centering problem becomes trivial with flexbox:

.center-container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
}

3. Equal-Height Elements

When you need columns or cards to have the same height regardless of content:

.card-container {
  display: flex;
  gap: 20px;
}

.card {
  flex: 1;
}

When to Use CSS Grid

CSS Grid is the better choice for:

1. Page-Level Layouts

For defining the overall structure of a page with header, footer, sidebar, and main content:

.page-layout {
  display: grid;
  grid-template-areas:
    "header header"
    "sidebar main"
    "footer footer";
  grid-template-columns: 250px 1fr;
  grid-template-rows: auto 1fr auto;
  min-height: 100vh;
}

2. Image Galleries or Card Layouts

When you need items to align both horizontally and vertically in a grid:

.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
}

3. Complex, Asymmetrical Layouts

When some elements need to span multiple rows or columns:

.dashboard {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-auto-rows: minmax(100px, auto);
  gap: 16px;
}

.feature-card {
  grid-column: span 2;
  grid-row: span 2;
}

Combining Both for Maximum Power

In many modern layouts, the most effective approach is to use Grid for the overall page structure and Flexbox for component-level alignment:

.page {
  display: grid;
  grid-template-columns: 1fr minmax(auto, 1200px) 1fr;
  grid-template-rows: auto 1fr auto;
}

.card {
  display: flex;
  flex-direction: column;
}

.card-footer {
  display: flex;
  justify-content: space-between;
  margin-top: auto;
}

By understanding the strengths of each system, you can build more maintainable and responsive layouts with cleaner, more semantic CSS.