Ratio
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="../assets/img/wide-2.svg" 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.
School kit
Meal pack
Shelter support
Monthly gift
Tree planting
Emergency fund
<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-1.svg" alt="School kit" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">School kit</p>
</div>
<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="Meal pack" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Meal pack</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-md overflow-hidden border">
<img src="../assets/img/product-3.svg" alt="Shelter support" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Shelter support</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="Monthly gift" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Monthly gift</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-md overflow-hidden border">
<img src="../assets/img/product-5.svg" alt="Tree planting" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Tree planting</p>
</div>
<div class="col-4 col-md-2">
<div class="ratio ratio-1x1 rounded-md overflow-hidden border">
<img src="../assets/img/product-6.svg" alt="Emergency fund" class="object-cover">
</div>
<p class="small truncate mt-1 mb-0">Emergency fund</p>
</div>
</div>4Cinematic hero banner
ratio-21x9 for a wide banner with a headline overlay.
Together we can change lives
<div class="ratio ratio-21x9 rounded-lg overflow-hidden">
<div>
<img src="../assets/img/wide-4.svg" 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">Together we can change lives</h3>
<p class="small mb-0 hidden sm:block">The new secure giving connects projects moving forward without extra tools.</p>
</div>
</div>
</div>5Map placeholder
A 4:3 box reserved for a map, showing the address until the map loads.
Brand name 1111 Cedar Lane, Singapore
<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"><i class="bi bi-geo-alt-fill" aria-hidden="true"></i></span><strong>Brand name 11</strong><span class="small text-muted">11 Cedar Lane, Singapore</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="../assets/img/photo-3.svg" alt="A guide to clean water" class="object-cover">
</div>
<figcaption class="small text-muted mt-1">3:2 · How we rebuilt our story</figcaption>
</figure>7Portrait team cards
A 3:4 portrait ratio (133.33%) for team photos in cards.
Samir Silva
HR Partner
Ravi Nguyen
Product Designer
Maya Whitaker
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="../assets/img/photo-5.svg" alt="Samir Silva" class="object-cover">
</div>
<div class="card-body py-2">
<h3 class="h6 mb-0">Samir Silva</h3>
<p class="small text-muted mb-0">HR Partner</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="../assets/img/photo-12.svg" alt="Ravi Nguyen" class="object-cover">
</div>
<div class="card-body py-2">
<h3 class="h6 mb-0">Ravi Nguyen</h3>
<p class="small text-muted mb-0">Product Designer</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="../assets/img/photo-4.svg" alt="Maya Whitaker" class="object-cover">
</div>
<div class="card-body py-2">
<h3 class="h6 mb-0">Maya Whitaker</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.
Tariq
Leo
Priya
Samir<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="../assets/img/photo-6.svg" alt="Story by Tariq Harlow" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Tariq</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="../assets/img/photo-7.svg" alt="Story by Leo Harlow" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Leo</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="../assets/img/photo-8.svg" alt="Story by Priya Larsen" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Priya</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="../assets/img/photo-9.svg" alt="Story by Samir Haddad" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Samir</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:59%">
</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:74%">
</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:38%">
</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:60%">
</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:80%">
</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:52%">
</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:52%">
</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:60%">
</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
How we rebuilt our story
Jan 12, 2026
<div class="card" style="max-width:22rem">
<div class="ratio ratio-16x9 card-img-top overflow-hidden">
<img src="../assets/img/photo-7.svg" alt="How we rebuilt our community" class="object-cover">
</div>
<div class="card-body">
<span class="badge text-bg-light border mb-2">insights</span>
<h3 class="h6">How we rebuilt our story</h3>
<p class="small text-muted mb-0">Jan 12, 2026</p>
</div>
</div>11Caption over a gradient
A 4:3 image with a gradient overlay so white caption text stays readable.
KyotoAnimal rescue
<div class="ratio ratio-4x3 rounded-lg overflow-hidden" style="max-width:24rem">
<div>
<img src="../assets/img/photo-9.svg" 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">Kyoto</strong><span class="small">Animal rescue</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="../assets/img/photo-2.svg" 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="../assets/img/square-4.svg" alt="Gallery photo 2" class="object-cover">
</div>
</div>
<div class="col-6">
<div class="ratio ratio-1x1 rounded-md overflow-hidden">
<img src="../assets/img/square-5.svg" alt="Gallery photo 3" class="object-cover">
</div>
</div>
<div class="col-12">
<div class="ratio ratio-21x9 rounded-md overflow-hidden">
<img src="../assets/img/wide-6.svg" 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 |
|---|---|---|
| Monthly gift | $301.99 |
| Tree planting | $369.50 |
| Shelter support | $451.50 |
<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-1.svg" alt="Monthly gift" class="object-cover"></div></td>
<td class="align-middle">Monthly gift</td>
<td class="align-middle text-end">$301.99</td>
</tr>
<tr>
<td style="width:4rem"><div class="ratio ratio-1x1 rounded-md overflow-hidden"><img src="../assets/img/product-2.svg" alt="Tree planting" class="object-cover"></div></td>
<td class="align-middle">Tree planting</td>
<td class="align-middle text-end">$369.50</td>
</tr>
<tr>
<td style="width:4rem"><div class="ratio ratio-1x1 rounded-md overflow-hidden"><img src="../assets/img/product-3.svg" alt="Shelter support" class="object-cover"></div></td>
<td class="align-middle">Shelter support</td>
<td class="align-middle text-end">$451.50</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" style="border-style:dashed!important">
<span class="text-3xl"><i class="bi bi-image" 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.
12:31NewWhat's new in relief
12:12How we rebuilt our release
9:03How we rebuilt our update
<div class="row g-3">
<div class="col-md-4">
<div class="ratio ratio-16x9 rounded-md overflow-hidden">
<div>
<img src="../assets/img/photo-4.svg" alt="" class="w-full h-full object-cover"><span class="absolute bottom-0 end-0 m-2 badge text-bg-dark">12:31</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">What's new in relief</p>
</div>
<div class="col-md-4">
<div class="ratio ratio-16x9 rounded-md overflow-hidden">
<div>
<img src="../assets/img/photo-5.svg" alt="" class="w-full h-full object-cover"><span class="absolute bottom-0 end-0 m-2 badge text-bg-dark">12:12</span>
</div>
</div>
<p class="small font-semibold mt-1 mb-0">How we rebuilt our release</p>
</div>
<div class="col-md-4">
<div class="ratio ratio-16x9 rounded-md overflow-hidden">
<div>
<img src="../assets/img/photo-6.svg" alt="" class="w-full h-full object-cover"><span class="absolute bottom-0 end-0 m-2 badge text-bg-dark">9:03</span>
</div>
</div>
<p class="small font-semibold mt-1 mb-0">How we rebuilt our update</p>
</div>
</div>17Media list
Fixed width 4:3 thumbnails beside article titles in a reading list.
Inside the fast story
Feb 25, 2026 · 12 min read
Inside the clear update
Sep 19, 2026 · 12 min read
How we rebuilt our plan
Jul 16, 2026 · 9 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="../assets/img/photo-8.svg" alt="" class="object-cover"></div></div><div><h3 class="h6 mb-1">Inside the fast story</h3><p class="small text-muted mb-0">Feb 25, 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="../assets/img/photo-9.svg" alt="" class="object-cover"></div></div><div><h3 class="h6 mb-1">Inside the clear update</h3><p class="small text-muted mb-0">Sep 19, 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="../assets/img/photo-10.svg" alt="" class="object-cover"></div></div><div><h3 class="h6 mb-1">How we rebuilt our plan</h3><p class="small text-muted mb-0">Jul 16, 2026 · 9 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="../assets/img/wide-8.svg" alt="Together we can change lives" 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-6.svg" alt="Diego Silva" class="object-cover">
</div>
<span class="small block truncate mt-1">Diego</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="Lea Harlow" class="object-cover">
</div>
<span class="small block truncate mt-1">Lea</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-5.svg" alt="Freya Ashford" class="object-cover">
</div>
<span class="small block truncate mt-1">Freya</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-6.svg" alt="Mason Novak" class="object-cover">
</div>
<span class="small block truncate mt-1">Mason</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>