Free · Fast · Privacy-first

CSS Flexbox Generator

Writing Flexbox CSS from scratch means looking up justify-content values, guessing whether align-items or align-content is the right property for the situation, and double-checking whether flex-direction has swapped which axis each alignment property affects this time. The FixTools Flexbox Generator shows you a live preview as you adjust each property, so you can see exactly how flex-direction, justify-content, align-items, align-content, flex-wrap, and gap interact before copying the finished ruleset into your stylesheet. Every change updates the preview immediately with sample items that mimic real content, which means the alignment behaviour you confirm in the tool is the alignment behaviour you will get in production.

⚡ Use Tool Now How it works

Cost: Free forever
Sign-up: Not required
Processing: In your browser
Privacy: Files stay local

⚡

Set flex-direction, justify-content, and align-items visually

🔒

Live preview updates as you change each property

✨

Includes gap, flex-wrap, and flex-grow controls

CSS Tool

Grid Flexbox Builder

All processing happens in your browser — your files are never uploaded to any server.

🚀Open Grid Flexbox Builder

100% Free · No account · Works on any device

What Flexbox Is and How a Visual Generator Reveals Its Alignment Logic

Flexbox is a one-dimensional layout model designed to arrange child elements along a single main axis, either horizontal when flex-direction is set to row (the default) or vertical when flex-direction is set to column. The cross axis runs perpendicular to the main axis, and most of Flexbox's alignment vocabulary boils down to controlling how items behave on these two axes. The justify-content property controls how items are spaced along the main axis, accepting center, flex-start, flex-end, space-between, space-around, and space-evenly, each producing a noticeably different distribution. The align-items property controls how items are positioned on the cross axis, with stretch, center, flex-start, and flex-end covering the vast majority of practical cases. The combination of these two properties is responsible for the majority of Flexbox layouts in the wild, and the visual generator shows exactly what each combination produces with real items inside a real container.

A visual Flexbox generator works by rendering a set of sample items inside a preview container and applying the Flexbox properties you select in real time, with no rebuild step or browser refresh required. When you switch justify-content from flex-start to space-between, you immediately see the items spread to the edges of the container with all extra space pushed into the gaps between them. When you change align-items from stretch to center, the items stop filling the full cross-axis height and sit precisely in the middle of the container. The generator then outputs a tidy CSS ruleset for the container: display flex, flex-direction, justify-content, align-items, and gap, in the order you would write them by hand. You copy that ruleset and apply it to your actual HTML container, and because the preview applies the same browser-native CSS engine, the result in your page matches the preview exactly down to the pixel.

Flexbox is the right choice over Grid when items should fill available space dynamically along one axis: navigation bars, button groups, form rows, input-plus-button pairs, tag clouds, breadcrumb trails, toolbar buttons, and icon rows. In all of these cases, the items themselves determine the layout size, and Flexbox adapts the container to fit them rather than forcing them into preset tracks. Grid is the right choice when the layout determines where items go, regardless of their content size, such as in image galleries, dashboards, and any structure where alignment across multiple rows matters. The visual generator lets you try both layout systems without writing a single line of CSS, which is the fastest way to confirm which system fits your particular component before you commit to the implementation.

Flexbox also handles dynamic content gracefully in ways that older techniques could not. When a label inside a button grows because of a translation, when a user adds an extra tag to a tag list, or when an icon is swapped for one with different dimensions, the Flexbox container quietly absorbs the change without breaking the surrounding layout. The flex-grow, flex-shrink, and flex-basis properties give you precise control over how items respond to changes in available space, and the generator exposes these as separate controls so you can confirm the response behaviour before deploying. This dynamic resilience is the practical reason Flexbox replaced floats and inline-block as the default layout system for component-level interfaces across the industry.

MDN: CSS Flexible Box Layout CSS Tricks: A Complete Guide to Grid

How to use this tool

💡

Open the Flexbox Generator, choose your flex-direction, set justify-content and align-items to the alignment you need, add a gap value, then click Copy CSS. The output is ready to paste into your component styles.

How It Works

Step-by-step guide to css flexbox generator:

1
Choose flex-direction
Select row to arrange items horizontally along the main axis or column to stack them vertically. The preview updates immediately to show the main axis direction and the cross axis perpendicular to it. Remember that switching direction also swaps which alignment property controls which axis, so keep an eye on the preview as you change it. The row-reverse and column-reverse values flip the source order visually without changing the underlying HTML.
2
Set justify-content
Pick the main-axis distribution from center, space-between, space-around, space-evenly, flex-start, or flex-end. Watch the preview items reposition as you switch between options to see exactly how each value distributes free space. space-between pushes items to opposite edges, space-around adds equal margins on both sides of each item, and space-evenly equalises the spaces including the outer edges. Choose the value that matches the spacing pattern in your design.
3
Set align-items
Choose the cross-axis alignment from stretch, center, flex-start, flex-end, or baseline. For row-direction layouts, this controls vertical alignment of items within the container height; for column layouts it controls horizontal alignment instead. The default stretch value makes items fill the cross axis, while center is the workhorse value for vertically centring navbar content. Test the result with items of different sizes to confirm the alignment behaves as expected.
4
Copy the ruleset
Click Copy CSS to copy the complete Flexbox container ruleset, including display flex, flex-direction, justify-content, align-items, and gap. Paste it directly into your component stylesheet on the container selector that wraps your items. The output is plain CSS with no vendor prefixes required for modern browsers, and it works inside any framework or styling solution from vanilla CSS to CSS-in-JS libraries.

Real-world examples

Common situations where this approach makes a real difference:

Navigation bar with logo and links

A developer uses the generator to produce a row-direction Flexbox container with justify-content: space-between and align-items: center for the site header. The output places a logo element at the left edge, a navigation list at the right edge, and vertically centres both within the header at any header height. The complete ruleset takes three seconds to generate and two lines to paste, replacing what used to be five or six lines of float-based CSS plus a clearfix. The result is robust against future link additions because Flexbox redistributes the items automatically without recomputing widths or breakpoints.

Centered call-to-action section

A designer needs a hero section where a heading, subheading, and button are centred both horizontally and vertically inside a full-viewport-height container. The generator produces a column-direction container with justify-content: center and align-items: center, plus a gap value for consistent spacing between the stacked elements. The items stack vertically and sit in the middle of the container at any height, including responsive heights that change between mobile and desktop. No magic numbers or negative margins are involved, and the centring continues to work even when content length changes.

Icon row in a feature card

A UI developer building a pricing card uses the generator with flex-direction: row, justify-content: flex-start, align-items: center, and gap: 12px to lay out an icon plus a label inside each feature item. Each icon and its label sit on the same baseline with consistent spacing, regardless of label length or icon dimensions. The gap property replaces the margin-right hacks that would otherwise need a :last-child override to avoid trailing space, which keeps the CSS shorter and prevents the subtle spacing bug where the final item visually drifts from the rest of the row.

Form row with input and button

A developer building a search bar wraps an input and a submit button in a Flexbox container with flex-direction: row and align-items: stretch. The button grows to match the input height automatically because stretch is the default cross-axis behaviour, which eliminates the chronic mismatch where the button would otherwise be a few pixels shorter than the input. Adding flex-grow: 1 to the input makes it fill all remaining width while the button stays at its natural size. The generator outputs this ruleset without any manual width calculation, and the result adapts to any container width.

When to use this guide

Use this when building a single-row or single-column component layout where items need to distribute space, align to an axis, or fill available width dynamically.

Pro tips

Get better results with these expert suggestions:

Use align-content for multi-row layouts

align-items controls cross-axis alignment for items within a single row, while align-content controls how multiple rows are distributed within the container when flex-wrap is enabled. They are separate properties and switching between them when items wrap is a common source of confusion in Flexbox layouts. If you set align-items hoping to control vertical row distribution and nothing happens, the property you actually need is align-content, which only takes effect when there is more than one wrapped row.

Set flex-shrink: 0 on fixed-size items

Flexbox shrinks items by default when the container is too narrow to accommodate the natural size of every child. If you have an icon, avatar, or logo that must stay at a fixed dimension, add flex-shrink: 0 to that specific item. Without it, the browser shrinks the icon alongside the text items, which breaks designs that depend on exact icon dimensions or pixel-perfect logos. This single property is the fix for the most common Flexbox surprise in production layouts.

Prefer gap over margin for spacing items

Using margin on flex items creates spacing issues at the first and last item unless you write :first-child and :last-child overrides to strip the outer margins. The gap property on the container applies spacing only between items and never on the outer edges, which is almost always the intended behaviour. gap is supported in all modern browsers for Flexbox since 2021, so unless you must support ancient browsers, gap is the better choice for cleaner CSS and predictable spacing that survives item count changes.

Test justify-content with different item counts

space-between and space-around behave noticeably differently when there is only one item in the container or when the item count drops to two. space-between with a single item pushes it to the left edge; space-around centres it; space-evenly also centres it. Check both the minimum and maximum item counts for your component to confirm the chosen value works correctly across all states, especially for components such as wizards or pagers that may render zero, one, two, or many items depending on the data.

FAQ

Frequently asked questions

justify-content distributes space along the main axis, which is horizontal when flex-direction is row and vertical when it is column. align-items positions items on the cross axis, which is the axis perpendicular to the main axis. In a row-direction container, justify-content controls horizontal spacing and align-items controls vertical positioning. Switching the container to column-direction swaps which axis each property affects, so the same property names now control the opposite dimension. The clearest way to internalise this is to remember that justify-content always talks about main-axis distribution and align-items always talks about cross-axis positioning, regardless of which physical direction those axes point in at the time.

Use Flexbox for one-dimensional layouts where items should flow and fill space dynamically along a single axis: navigation bars, button groups, card rows, form rows, breadcrumb trails, and tag clouds. Use Grid for two-dimensional layouts where both row and column positions matter simultaneously: page skeletons, dashboards, image galleries, and pricing tables where columns must align across multiple rows. If you are uncertain which to use, try the Flexbox generator first because Flexbox produces simpler CSS for the common one-axis case. If your layout requires items to align across multiple rows or has a complex grid structure, switch to the Grid generator and rebuild the layout there for comparison.

flex-grow controls how much of the remaining free space in the container a flex item claims when there is space left over after the items reach their natural size. A value of 1 means the item grows to fill its share of the available space. A value of 2 means the item takes twice as much free space as a sibling with flex-grow: 1. A value of 0 (the default) means the item does not grow beyond its natural size at all. The classic use case is adding flex-grow: 1 to an input inside a row container, which makes the input fill all the width not occupied by fixed-size siblings such as a label or a button.

Yes. Setting flex-direction: column on a container makes it a vertical Flexbox where items stack top to bottom along the main axis. In this configuration, justify-content now controls vertical distribution instead of horizontal, and align-items controls horizontal alignment instead of vertical. This is how you build stacked card content, sidebar navigation lists, vertical button groups, and any vertically arranged group of elements that needs consistent spacing. The column-reverse value flips the stacking direction so items appear bottom-up, which is useful for chat interfaces and notification feeds where new content should appear at the bottom while older content stays above.

flex-wrap: wrap allows flex items to move onto a new line when they exceed the container width, turning what is normally a single-row layout into a multi-row one that adapts to the available space. Without it, items shrink to fit on one line regardless of how narrow the container becomes, which can compress items below readable sizes. Enable flex-wrap when you want items to flow naturally onto additional rows at narrow widths. For navigation links that should wrap onto two rows on mobile, for a row of tags that may overflow at any container width, or for a list of filter chips, flex-wrap is the right approach. Pair it with flex-basis to control how many items fit per row.

The gap property on a flex container sets the space between flex items, exactly the same way it works in CSS Grid. It accepts one value for equal spacing in both directions, or two values to set row-gap and column-gap separately if you need different vertical and horizontal spacing in a wrapped layout. Gap does not add space before the first item or after the last item, which makes it cleaner than using margin on individual items where you would otherwise need :first-child and :last-child overrides to strip the outer margins. Gap for Flexbox has been supported in all modern browsers since 2021, with full support in Chrome, Firefox, Safari, and Edge.

Yes. This is one of the most common and explicitly recommended patterns in modern CSS layout design. A Grid container defines the outer page skeleton with rows and columns at the macro level, and inside each grid cell, a Flexbox container handles the inner component layout at the micro level. For example, a header cell in a page-level grid uses Flexbox internally to arrange a logo on the left and navigation links on the right. Grid and Flexbox complement each other rather than compete, and the specifications were written with this combination in mind. There is no performance penalty or browser bug from nesting them, and the resulting CSS is more readable than trying to force either system to do both jobs.

Yes. The generator outputs standard CSS Flexbox properties with no vendor prefixes required for any modern browser. The output uses display flex, flex-direction, justify-content, align-items, and gap, all of which are fully supported in Chrome, Firefox, Safari, and Edge without prefixes for years. For projects that still need Internet Explorer 11 support, -webkit- and -ms- prefixes can be added to the output by hand or by running the CSS through an autoprefixer step in your build pipeline, but IE11 global market share is now below 0.5% and most projects no longer include those prefixes. The generated CSS is also framework-agnostic, so it slots into Tailwind, Bootstrap, or vanilla projects without modification.

Use flex-direction: row-reverse or column-reverse to flip the visual order of items along the main axis while leaving the HTML source order intact. Alternatively, set the order property on individual items: items with lower order values render before items with higher order values, with the default order being 0. Negative values are allowed, so order: -1 on one item pushes it to the front. Be cautious when using either approach in interactive interfaces because screen readers and keyboard navigation follow the DOM source order, not the visual order. If you reorder items for visual reasons only, the experience for assistive technology users may diverge from what sighted users see.

Flexbox sizing follows a specific algorithm that often overrides the width property. The flex-basis property sets the ideal size before space is distributed, and flex-grow and flex-shrink then expand or contract items from that starting size based on the available container space. If you set width: 200px on a flex item, the browser respects it as the initial size, but flex-shrink: 1 (the default) still allows that item to shrink below 200px when the container is too narrow. To enforce a hard width, set flex-shrink: 0 alongside the width value, or use min-width to prevent shrinking below your target. For a fully predictable size, prefer flex-basis with explicit flex-grow and flex-shrink values.