Flexbox vs Grid: Which One Should You Use?

One dimension or two

Flexbox works in one direction at a time, a row or a column. Items can wrap onto new lines, but each line is laid out on its own, so items in different lines do not align with each other.

Grid works in rows and columns at once. Every item sits in cells of the same grid, so things line up both across and down, no matter what is inside them.

Content first or layout first

Flexbox starts from the content: each item's size comes from what it contains, and the remaining space is shared out. Grid starts from the layout: you define the tracks, and items fill them. Ask yourself whether the sizes should come from the content or from the design.

Where Flexbox fits best

• A navigation bar with links of different lengths.
• A button with an icon and a label, centred vertically.
• A row of tags or chips that wrap naturally.
• Pushing one item to the far end, such as a logo left and a menu right.

.nav {
  display: flex;
  align-items: center;
  gap: 1rem;
}
.nav .logo { margin-right: auto; } /* pushes everything else to the right */

Where Grid fits best

• Page layouts with a header, sidebar, main area and footer.
• Card galleries where every card should line up in neat columns.
• Forms with labels in one column and inputs in another.
• Anything where items must align across rows as well as along them.

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
}

That one rule makes a responsive gallery with no media queries: as many columns of at least 240 pixels as will fit, sharing the leftover space equally.

Use both

It is not a choice for the whole site. A common, sensible pattern is Grid for the page and the card gallery, and Flexbox inside each card for the row of buttons at the bottom. Both support gap, both can centre things, and nesting one inside the other is normal.