The ratio helper keeps a box at a fixed aspect ratio whatever its width, which is perfect for media placeholders, thumbnails, galleries and banners. Pick ratio-1x1, ratio-4x3, ratio-16x9 or ratio-21x9, or set any ratio with the --ui-aspect-ratio variable.
1The four built-in ratios
ratio-1x1, ratio-4x3, ratio-16x9 and ratio-21x9 next to each other, filled with a plain div.
1:1
4:3
16:9
21:9
<div class="row g-3">
<div class="col-6 col-md-3">
<div class="ratio ratio-1x1">
<div class="flex items-center justify-center bg-primary-subtle text-primary-emphasis border border-primary/30 rounded-md font-semibold">
1:1
</div>
</div>
</div>
<div class="col-6 col-md-3">
<div class="ratio ratio-4x3">
<div class="flex items-center justify-center bg-primary-subtle text-primary-emphasis border border-primary/30 rounded-md font-semibold">
4:3
</div>
</div>
</div>
<div class="col-6 col-md-3">
<div class="ratio ratio-16x9">
<div class="flex items-center justify-center bg-primary-subtle text-primary-emphasis border border-primary/30 rounded-md font-semibold">
16:9
</div>
</div>
</div>
<div class="col-6 col-md-3">
<div class="ratio ratio-21x9">
<div class="flex items-center justify-center bg-primary-subtle text-primary-emphasis border border-primary/30 rounded-md font-semibold">
21:9
</div>
</div>
</div>
</div>2Video placeholder
A 16:9 poster image with a centred play button, ready for a video player of your choice.
<div class="ratio ratio-16x9 rounded-md overflow-hidden" style="max-width:36rem">
<div>
<img src="https://images.unsplash.com/photo-1718985342149-7178154e0aee?auto=format&fit=crop&w=1600&h=700&q=70" alt="Video poster" class="w-full h-full object-cover">
<button type="button" class="btn btn-light rounded-full absolute top-1/2 start-1/2 -translate-x-1/2 -translate-y-1/2 shadow-md" aria-label="Play video"><i class="bi bi-play-fill" aria-hidden="true"></i></button>
</div>
</div>3Square product thumbnails
ratio-1x1 with object-fit-cover gives every product the same tile, whatever the photo size.
Canvas tote
Running cap
Leather wallet
Cotton throw
Linen shirt
Hand cream
<div class="row g-2">
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-md overflow-hidden border">
<img src="../assets/img/product-2.svg" alt="Canvas tote" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Canvas tote</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-md overflow-hidden border">
<img src="../assets/img/product-7.svg" alt="Running cap" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Running cap</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-md overflow-hidden border">
<img src="../assets/img/product-4.svg" alt="Leather wallet" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Leather wallet</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-md overflow-hidden border">
<img src="../assets/img/product-9.svg" alt="Cotton throw" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Cotton throw</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-md overflow-hidden border">
<img src="../assets/img/product-1.svg" alt="Linen shirt" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Linen shirt</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-md overflow-hidden border">
<img src="../assets/img/product-11.svg" alt="Hand cream" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Hand cream</p>
</div>
</div>4Cinematic hero banner
ratio-21x9 for a wide banner with a headline overlay.
The new collection has landed
<div class="ratio ratio-21x9 rounded-lg overflow-hidden">
<div>
<img src="https://images.unsplash.com/photo-1521335629791-ce4aec67dd15?auto=format&fit=crop&w=1600&h=700&q=70" alt="" class="w-full h-full object-cover">
<div class="absolute bottom-0 start-0 p-4 md:p-6 text-white" style="background:rgba(0,0,0,.45)">
<h3 class="h4 mb-1">The new collection has landed</h3>
<p class="small mb-0 hidden sm:block">Our packaging is plastic-free and every delivery is carbon-neutral.</p>
</div>
</div>
</div>5Map placeholder
A 4:3 box reserved for a map, showing the address until the map loads.
Xenoara Pro121 Orchard Close, Valencia
<div class="ratio ratio-4x3" style="max-width:24rem">
<div class="flex flex-col items-center justify-center bg-surface-3 border rounded-md text-center p-4">
<span class="text-4xl text-primary-ink"><i class="bi bi-geo-alt-fill" aria-hidden="true"></i></span><strong>Xenoara Pro</strong><span class="small text-muted">121 Orchard Close, Valencia</span>
</div>
</div>6Custom 3:2 photo
Any ratio works with the --ui-aspect-ratio variable: 2 / 3 = 66.67% for classic photo prints.
<figure class="mb-0" style="max-width:28rem">
<div class="ratio rounded-md overflow-hidden" style="--ui-aspect-ratio:66.67%">
<img src="https://images.unsplash.com/photo-1567401893414-76b7b1e5a7a5?auto=format&fit=crop&w=1200&h=800&q=70" alt="How to choose the right product" class="object-cover">
</div>
<figcaption class="small text-muted mt-1">3:2 · Meet the makers behind our ceramics</figcaption>
</figure>7Portrait team cards
A 3:4 portrait ratio (133.33%) for team photos in cards.
Hana Harlow
Frontend Engineer
Mia Varga
Project Manager
Samir Brennan
Marketing Lead
<div class="row g-3">
<div class="col-6 col-md-4">
<div class="card h-full">
<div class="ratio card-img-top overflow-hidden" style="--ui-aspect-ratio:133.33%">
<img src="https://images.unsplash.com/photo-1567401893414-76b7b1e5a7a5?auto=format&fit=crop&w=1200&h=800&q=70" alt="Hana Harlow" class="object-cover">
</div>
<div class="card-body py-2">
<h3 class="h6 mb-0">Hana Harlow</h3>
<p class="small text-muted mb-0">Frontend Engineer</p>
</div>
</div>
</div>
<div class="col-6 col-md-4">
<div class="card h-full">
<div class="ratio card-img-top overflow-hidden" style="--ui-aspect-ratio:133.33%">
<img src="https://images.unsplash.com/photo-1567401893414-76b7b1e5a7a5?auto=format&fit=crop&w=1200&h=800&q=70" alt="Mia Varga" class="object-cover">
</div>
<div class="card-body py-2">
<h3 class="h6 mb-0">Mia Varga</h3>
<p class="small text-muted mb-0">Project Manager</p>
</div>
</div>
</div>
<div class="col-6 col-md-4">
<div class="card h-full">
<div class="ratio card-img-top overflow-hidden" style="--ui-aspect-ratio:133.33%">
<img src="https://images.unsplash.com/photo-1580418835996-7783da1c3c6c?auto=format&fit=crop&w=1200&h=800&q=70" alt="Samir Brennan" class="object-cover">
</div>
<div class="card-body py-2">
<h3 class="h6 mb-0">Samir Brennan</h3>
<p class="small text-muted mb-0">Marketing Lead</p>
</div>
</div>
</div>
</div>8Vertical stories
A 9:16 ratio (177.78%) for phone sized stories or short clips in a scrolling row.
Mason
Nora
Zoe
Theo<div class="flex gap-2 overflow-auto pb-1">
<div class="shrink-0" style="width:7rem">
<div class="ratio rounded-lg overflow-hidden" style="--ui-aspect-ratio:177.78%">
<div>
<img src="https://images.unsplash.com/photo-1630905119003-329447458f85?auto=format&fit=crop&w=1200&h=800&q=70" alt="Story by Mason Ashford" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Mason</span>
</div>
</div>
</div>
<div class="shrink-0" style="width:7rem">
<div class="ratio rounded-lg overflow-hidden" style="--ui-aspect-ratio:177.78%">
<div>
<img src="https://images.unsplash.com/photo-1521335629791-ce4aec67dd15?auto=format&fit=crop&w=1200&h=800&q=70" alt="Story by Nora Kowalski" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Nora</span>
</div>
</div>
</div>
<div class="shrink-0" style="width:7rem">
<div class="ratio rounded-lg overflow-hidden" style="--ui-aspect-ratio:177.78%">
<div>
<img src="https://images.unsplash.com/photo-1573612664822-d7d347da7b80?auto=format&fit=crop&w=1200&h=800&q=70" alt="Story by Zoe Duarte" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Zoe</span>
</div>
</div>
</div>
<div class="shrink-0" style="width:7rem">
<div class="ratio rounded-lg overflow-hidden" style="--ui-aspect-ratio:177.78%">
<div>
<img src="https://images.unsplash.com/photo-1443884590026-2e4d21aee71c?auto=format&fit=crop&w=1200&h=800&q=70" alt="Story by Theo Carter" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Theo</span>
</div>
</div>
</div>
</div>9Chart area
A 16:9 box that keeps a simple bar chart in proportion on every screen.
Monthly bookings
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
<div class="card" style="max-width:36rem">
<div class="card-header small font-semibold">
Monthly bookings
</div>
<div class="card-body">
<div class="ratio ratio-16x9">
<div class="flex items-end gap-2" role="img" aria-label="Bar chart of monthly bookings">
<div class="flex-auto flex flex-col justify-end items-center h-full">
<div class="w-full bg-primary rounded-t-md" style="height:46%">
</div>
<span class="small text-muted">Jan</span>
</div>
<div class="flex-auto flex flex-col justify-end items-center h-full">
<div class="w-full bg-primary rounded-t-md" style="height:46%">
</div>
<span class="small text-muted">Feb</span>
</div>
<div class="flex-auto flex flex-col justify-end items-center h-full">
<div class="w-full bg-primary rounded-t-md" style="height:63%">
</div>
<span class="small text-muted">Mar</span>
</div>
<div class="flex-auto flex flex-col justify-end items-center h-full">
<div class="w-full bg-primary rounded-t-md" style="height:32%">
</div>
<span class="small text-muted">Apr</span>
</div>
<div class="flex-auto flex flex-col justify-end items-center h-full">
<div class="w-full bg-primary rounded-t-md" style="height:21%">
</div>
<span class="small text-muted">May</span>
</div>
<div class="flex-auto flex flex-col justify-end items-center h-full">
<div class="w-full bg-primary rounded-t-md" style="height:40%">
</div>
<span class="small text-muted">Jun</span>
</div>
<div class="flex-auto flex flex-col justify-end items-center h-full">
<div class="w-full bg-primary rounded-t-md" style="height:56%">
</div>
<span class="small text-muted">Jul</span>
</div>
<div class="flex-auto flex flex-col justify-end items-center h-full">
<div class="w-full bg-primary rounded-t-md" style="height:64%">
</div>
<span class="small text-muted">Aug</span>
</div>
</div>
</div>
</div>
</div>10Blog card cover
ratio-16x9 as a card image keeps every post card in a grid the same height.
insights
A three-step skincare routine that works
Oct 7, 2026
<div class="card" style="max-width:22rem">
<div class="ratio ratio-16x9 card-img-top overflow-hidden">
<img src="https://images.unsplash.com/photo-1521335629791-ce4aec67dd15?auto=format&fit=crop&w=1200&h=800&q=70" alt="Five pieces for a capsule wardrobe" class="object-cover">
</div>
<div class="card-body">
<span class="badge text-bg-light border mb-2">insights</span>
<h3 class="h6">A three-step skincare routine that works</h3>
<p class="small text-muted mb-0">Oct 7, 2026</p>
</div>
</div>11Caption over a gradient
A 4:3 image with a gradient overlay so white caption text stays readable.
OsloSecure checkout
<div class="ratio ratio-4x3 rounded-lg overflow-hidden" style="max-width:24rem">
<div>
<img src="https://images.unsplash.com/photo-1443884590026-2e4d21aee71c?auto=format&fit=crop&w=1200&h=800&q=70" alt="" class="w-full h-full object-cover">
<div class="absolute bottom-0 w-full p-4 text-white" style="background:linear-gradient(transparent,rgba(0,0,0,.7))">
<strong class="block">Oslo</strong><span class="small">Secure checkout</span>
</div>
</div>
</div>12Mixed ratio gallery
Combining 1:1, 4:3 and 16:9 tiles in one responsive grid.
<div class="row g-2">
<div class="col-md-6">
<div class="ratio ratio-4x3 rounded-md overflow-hidden">
<img src="https://images.unsplash.com/photo-1441984904996-e0b6ba687e04?auto=format&fit=crop&w=1200&h=800&q=70" alt="Gallery photo 1" class="object-cover">
</div>
</div>
<div class="col-md-6">
<div class="row g-2">
<div class="col-6">
<div class="ratio ratio-1x1 rounded-md overflow-hidden">
<img src="https://images.unsplash.com/photo-1598305762558-328f599df683?auto=format&fit=crop&w=800&h=800&q=70" alt="Gallery photo 2" class="object-cover">
</div>
</div>
<div class="col-6">
<div class="ratio ratio-1x1 rounded-md overflow-hidden">
<img src="https://images.unsplash.com/photo-1601647998829-ee316a565aea?auto=format&fit=crop&w=800&h=800&q=70" alt="Gallery photo 3" class="object-cover">
</div>
</div>
<div class="col-12">
<div class="ratio ratio-21x9 rounded-md overflow-hidden">
<img src="https://images.unsplash.com/photo-1443884590026-2e4d21aee71c?auto=format&fit=crop&w=1600&h=700&q=70" alt="Gallery photo 4" class="object-cover">
</div>
</div>
</div>
</div>
</div>13Thumbnails in table cells
A small ratio-1x1 box keeps order line images square inside a table.
| Image | Item | Price |
|---|---|---|
 | Ceramic mug | $21.00 |
 | Glass bottle | $25.00 |
 | Wool scarf | $49.00 |
<table class="table align-middle mb-0">
<thead>
<tr>
<th scope="col"><span class="sr-only">Image</span></th>
<th scope="col">Item</th>
<th scope="col" class="text-end">Price</th>
</tr>
</thead>
<tbody>
<tr>
<td style="width:4rem"><div class="ratio ratio-1x1 rounded-md overflow-hidden"><img src="../assets/img/product-3.svg" alt="Ceramic mug" class="object-cover"></div></td>
<td class="align-middle">Ceramic mug</td>
<td class="align-middle text-end">$21.00</td>
</tr>
<tr>
<td style="width:4rem"><div class="ratio ratio-1x1 rounded-md overflow-hidden"><img src="../assets/img/product-8.svg" alt="Glass bottle" class="object-cover"></div></td>
<td class="align-middle">Glass bottle</td>
<td class="align-middle text-end">$25.00</td>
</tr>
<tr>
<td style="width:4rem"><div class="ratio ratio-1x1 rounded-md overflow-hidden"><img src="../assets/img/product-5.svg" alt="Wool scarf" class="object-cover"></div></td>
<td class="align-middle">Wool scarf</td>
<td class="align-middle text-end">$49.00</td>
</tr>
</tbody>
</table>14Empty cover placeholder
A dashed 4:3 area that reserves space for an image that has not been chosen yet.
No cover image yet
<div class="ratio ratio-4x3" style="max-width:20rem">
<div class="flex flex-col items-center justify-center border border-2 border-secondary/30 rounded-lg text-muted wt-border-dashed">
<span class="text-3xl"><i class="bi bi-image-fill" aria-hidden="true"></i></span><span class="small">No cover image yet</span>
</div>
</div>15Colour swatches
Empty square ratios make perfect colour swatches for a style guide.
primary
primary
secondary
secondary
success
success
info
info
warning
warning
danger
danger
<div class="row g-2">
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-lg bg-primary">
<span class="sr-only">primary</span>
</div>
<p class="small text-center mt-1 mb-0">primary</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-lg bg-secondary">
<span class="sr-only">secondary</span>
</div>
<p class="small text-center mt-1 mb-0">secondary</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-lg bg-success">
<span class="sr-only">success</span>
</div>
<p class="small text-center mt-1 mb-0">success</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-lg bg-info">
<span class="sr-only">info</span>
</div>
<p class="small text-center mt-1 mb-0">info</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-lg bg-warning">
<span class="sr-only">warning</span>
</div>
<p class="small text-center mt-1 mb-0">warning</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-lg bg-danger">
<span class="sr-only">danger</span>
</div>
<p class="small text-center mt-1 mb-0">danger</p>
</div>
</div>16Video thumbnails with badges
Duration and status badges positioned over 16:9 thumbnails.
8:41NewOur guide to gifts under $50
8:56Looking back at a busy season
2:41How to care for linen so it lasts for years
<div class="row g-3">
<div class="col-md-4">
<div class="ratio ratio-16x9 rounded-md overflow-hidden">
<div>
<img src="https://images.unsplash.com/photo-1567958451986-2de427a4a0be?auto=format&fit=crop&w=1200&h=800&q=70" alt="" class="w-full h-full object-cover"><span class="absolute bottom-0 end-0 m-2 badge text-bg-dark">8:41</span><span class="absolute top-0 start-0 m-2 badge text-bg-danger">New</span>
</div>
</div>
<p class="small font-semibold mt-1 mb-0">Our guide to gifts under $50</p>
</div>
<div class="col-md-4">
<div class="ratio ratio-16x9 rounded-md overflow-hidden">
<div>
<img src="https://images.unsplash.com/photo-1718985342149-7178154e0aee?auto=format&fit=crop&w=1200&h=800&q=70" alt="" class="w-full h-full object-cover"><span class="absolute bottom-0 end-0 m-2 badge text-bg-dark">8:56</span>
</div>
</div>
<p class="small font-semibold mt-1 mb-0">Looking back at a busy season</p>
</div>
<div class="col-md-4">
<div class="ratio ratio-16x9 rounded-md overflow-hidden">
<div>
<img src="https://images.unsplash.com/photo-1630905119003-329447458f85?auto=format&fit=crop&w=1200&h=800&q=70" alt="" class="w-full h-full object-cover"><span class="absolute bottom-0 end-0 m-2 badge text-bg-dark">2:41</span>
</div>
</div>
<p class="small font-semibold mt-1 mb-0">How to care for linen so it lasts for years</p>
</div>
</div>17Media list
Fixed width 4:3 thumbnails beside article titles in a reading list.
A small guide to a calmer home
Oct 28, 2025 · 7 min read
Inside our new autumn collection
Sep 6, 2026 · 12 min read
Five things we learned this year
Jun 30, 2026 · 12 min read
<ul class="list-unstyled mb-0 vstack gap-4">
<li class="flex gap-4"><div class="shrink-0" style="width:6rem"><div class="ratio ratio-4x3 rounded-md overflow-hidden"><img src="https://images.unsplash.com/photo-1573612664822-d7d347da7b80?auto=format&fit=crop&w=1200&h=800&q=70" alt="" class="object-cover"></div></div><div><h3 class="h6 mb-1">A small guide to a calmer home</h3><p class="small text-muted mb-0">Oct 28, 2025 · 7 min read</p></div></li>
<li class="flex gap-4"><div class="shrink-0" style="width:6rem"><div class="ratio ratio-4x3 rounded-md overflow-hidden"><img src="https://images.unsplash.com/photo-1443884590026-2e4d21aee71c?auto=format&fit=crop&w=1200&h=800&q=70" alt="" class="object-cover"></div></div><div><h3 class="h6 mb-1">Inside our new autumn collection</h3><p class="small text-muted mb-0">Sep 6, 2026 · 12 min read</p></div></li>
<li class="flex gap-4"><div class="shrink-0" style="width:6rem"><div class="ratio ratio-4x3 rounded-md overflow-hidden"><img src="https://images.unsplash.com/photo-1598305762558-328f599df683?auto=format&fit=crop&w=1200&h=800&q=70" alt="" class="object-cover"></div></div><div><h3 class="h6 mb-1">Five things we learned this year</h3><p class="small text-muted mb-0">Jun 30, 2026 · 12 min read</p></div></li>
</ul>18Responsive ratio
A small custom class changes --ui-aspect-ratio per breakpoint: square on phones, 21:9 on tablets and up.
<div class="ratio hp-ratio-resp rounded-lg overflow-hidden">
<img src="https://images.unsplash.com/photo-1601647998829-ee316a565aea?auto=format&fit=crop&w=1600&h=700&q=70" alt="Thoughtful goods for a simpler home" class="object-cover">
</div>19Round avatars
ratio-1x1 with rounded-circle keeps profile pictures perfectly round even when the source is not square.
<div class="flex flex-wrap gap-4">
<div class="text-center" style="width:5rem">
<div class="ratio ratio-1x1 rounded-full overflow-hidden border border-2 border-primary">
<img src="../assets/img/avatar-9.svg" alt="Omar Tanaka" class="object-cover">
</div>
<span class="small block truncate mt-1">Omar</span>
</div>
<div class="text-center" style="width:5rem">
<div class="ratio ratio-1x1 rounded-full overflow-hidden border border-2 border-primary">
<img src="../assets/img/avatar-3.svg" alt="Jonah Whitaker" class="object-cover">
</div>
<span class="small block truncate mt-1">Jonah</span>
</div>
<div class="text-center" style="width:5rem">
<div class="ratio ratio-1x1 rounded-full overflow-hidden border border-2 border-primary">
<img src="../assets/img/avatar-2.svg" alt="Maya Fischer" class="object-cover">
</div>
<span class="small block truncate mt-1">Maya</span>
</div>
<div class="text-center" style="width:5rem">
<div class="ratio ratio-1x1 rounded-full overflow-hidden border border-2 border-primary">
<img src="../assets/img/avatar-12.svg" alt="Mateo Duarte" class="object-cover">
</div>
<span class="small block truncate mt-1">Mateo</span>
</div>
</div>20Loading skeleton
A 16:9 placeholder block with placeholder-glow while the real image and text load.
The skeleton reserves the exact space, so the page does not jump when content arrives.
<div class="card" style="max-width:22rem" aria-hidden="true">
<div class="ratio ratio-16x9 placeholder-glow">
<span class="placeholder"></span>
</div>
<div class="card-body placeholder-glow">
<span class="placeholder col-7 mb-2"></span><span class="placeholder col-4"></span>
</div>
</div>
<p class="small text-muted mt-2 mb-0">The skeleton reserves the exact space, so the page does not jump when content arrives.</p>