📐 CSS Flexbox Generator
By ToolNimba Web Dev Team · Updated 2026-06-19
Pick the properties and the preview plus the CSS update live.
Flexbox is the CSS layout model for arranging items in a single row or column, and this generator lets you see exactly how the main properties behave. Pick a flex-direction, choose how items line up along the main and cross axes, set wrapping and gap, and watch a live preview of several flex items rearrange instantly. When it looks right, copy the generated CSS straight into your stylesheet.
What is the Flexbox Generator?
Flexbox (the CSS Flexible Box Layout) solves a problem that plagued web layout for years: distributing space and aligning items along one dimension without floats, table hacks or manual margins. You turn an element into a flex container with display: flex, and its direct children become flex items that you can align, space and order with a handful of properties. It is the go-to tool for navigation bars, button rows, card toolbars, centering a box, and any layout that flows in one direction.
Every flex container has two axes. The main axis runs in the direction set by flex-direction (row goes left to right, column goes top to bottom), and the cross axis runs perpendicular to it. This matters because justify-content always aligns items along the main axis, while align-items aligns them along the cross axis. Switch flex-direction from row to column and the two properties effectively swap which way they push items, which is the single most common source of confusion for people learning flexbox.
The remaining controls fine-tune the layout. flex-wrap decides whether items stay on one line (nowrap) or spill onto new lines (wrap) when they run out of room, which is the foundation of simple responsive grids. gap adds consistent spacing between items without margins, so you do not have to strip the margin off the last child. Together, flex-direction, justify-content, align-items, flex-wrap and gap cover the large majority of everyday layout needs, and this tool shows each one in isolation so you can build an intuition for how they combine.
When to use it
- Centering a box both horizontally and vertically with justify-content: center and align-items: center.
- Building a navigation bar that pushes the logo left and links right using space-between.
- Laying out a row of cards or buttons with even gaps and consistent vertical alignment.
- Experimenting with row versus column direction to understand which axis each property controls.
- Creating a simple wrapping grid of tags or chips that reflows on narrow screens.
How to use the Flexbox Generator
- Choose a flex-direction (row or column) to set the main axis.
- Pick justify-content to space items along the main axis.
- Pick align-items to align items along the cross axis.
- Set flex-wrap and the gap, and adjust the number of preview items to taste.
- Read the live preview, then click Copy to grab the generated CSS.
Formula & method
Worked examples
Perfectly center a single box inside its container.
- Set display: flex on the container.
- Keep flex-direction: row so the main axis is horizontal.
- Set justify-content: center to center along the main (horizontal) axis.
- Set align-items: center to center along the cross (vertical) axis.
Result: The item sits dead center both horizontally and vertically.
A navbar with the logo on the left and links on the right.
- Set display: flex and flex-direction: row.
- Set justify-content: space-between so the first and last items hug the edges.
- Set align-items: center to vertically center every item on the bar.
- Set flex-wrap: nowrap so the bar stays on one line.
Result: Logo pinned left, links pinned right, all vertically centered on one row.
What each flex container property controls
| Property | Controls | Common values |
|---|---|---|
| flex-direction | Direction of the main axis | row, row-reverse, column, column-reverse |
| justify-content | Spacing along the main axis | flex-start, center, space-between, space-evenly |
| align-items | Alignment along the cross axis | stretch, flex-start, center, baseline |
| flex-wrap | Single line or wrap to new lines | nowrap, wrap, wrap-reverse |
| gap | Space between items | Any length, for example 12px or 1rem |
justify-content values and how they distribute items
| Value | Effect |
|---|---|
| flex-start | Items packed to the start of the main axis. |
| center | Items packed to the center of the main axis. |
| space-between | First and last items at the edges, equal space between. |
| space-around | Equal space around each item (half-size at the ends). |
| space-evenly | Equal space between all items and the edges. |
Common mistakes to avoid
- Mixing up justify-content and align-items. justify-content works along the main axis and align-items along the cross axis. The moment you change flex-direction from row to column, the two swap which way they move items. If centering is not working, check your direction first.
- Forgetting display: flex on the parent. Flex properties only do anything once the container has display: flex (or inline-flex). Setting justify-content on a plain block element has no effect at all.
- Expecting align-items: stretch to work with a fixed height. stretch only fills the cross axis when items have no explicit size in that direction. If an item has a set height (in a row) it will not stretch, so remove the size to let it grow.
- Confusing gap with margins. gap adds space only between items, never on the outer edges, so you do not get a stray margin on the last child. Reaching for margins instead often leaves uneven spacing at the ends.
Glossary
- Flex container
- An element with display: flex (or inline-flex) whose direct children become flex items.
- Flex item
- A direct child of a flex container, positioned and aligned by the flex properties.
- Main axis
- The primary axis set by flex-direction, along which justify-content distributes items.
- Cross axis
- The axis perpendicular to the main axis, along which align-items aligns items.
- gap
- A property that sets consistent spacing between flex items without using margins.
Frequently asked questions
What is a CSS flexbox generator?
It is a visual tool that lets you set the main flexbox properties (flex-direction, justify-content, align-items, flex-wrap and gap) and see a live preview of how items arrange, then copy the matching CSS into your project.
What is the difference between justify-content and align-items?
justify-content aligns items along the main axis (the direction of flex-direction), while align-items aligns them along the cross axis (perpendicular to it). With flex-direction: row, justify-content moves items horizontally and align-items moves them vertically.
How do I center an element with flexbox?
Set display: flex on the parent, then justify-content: center and align-items: center. The child will sit centered along both axes. This works for centering one item or a group of items.
When should I use flexbox instead of CSS grid?
Flexbox is best for one-dimensional layouts, a single row or column, such as navbars, button groups and toolbars. CSS grid is built for two-dimensional layouts with explicit rows and columns. Many pages use both, grid for the overall structure and flexbox inside components.
What does flex-wrap do?
flex-wrap controls whether items stay on a single line (nowrap) or flow onto additional lines when they run out of space (wrap). Using wrap is the simplest way to make a row of items reflow on narrow screens.
Is the gap property well supported?
Yes. The gap property in flexbox is supported in all current major browsers, so it is safe to use for spacing between items instead of margins in any modern project.