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="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.

Running cap

Glass bottle

Rain jacket

Ceramic mug

Leather wallet

Desk lamp

<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-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-8.svg" alt="Glass bottle" class="object-cover">
    </div>
    <p class="small truncate mt-1 mb-0">Glass bottle</p>
  </div>
  <div class="col-4 col-md-2">
    <div class="ratio ratio-1x1 rounded-md overflow-hidden border">
      <img src="../assets/img/product-12.svg" alt="Rain jacket" class="object-cover">
    </div>
    <p class="small truncate mt-1 mb-0">Rain jacket</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="Ceramic mug" class="object-cover">
    </div>
    <p class="small truncate mt-1 mb-0">Ceramic mug</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-6.svg" alt="Desk lamp" class="object-cover">
    </div>
    <p class="small truncate mt-1 mb-0">Desk lamp</p>
  </div>
</div>

4Cinematic hero banner

ratio-21x9 for a wide banner with a headline overlay.

Style that works as hard as you do

Order before 2 pm and most items leave our warehouse the same day.

<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">Style that works as hard as you do</h3>
      <p class="small mb-0 hidden sm:block">Order before 2 pm and most items leave our warehouse the same day.</p>
    </div>
  </div>
</div>

5Map placeholder

A 4:3 box reserved for a map, showing the address until the map loads.

Mira Point263 Orchard Close, Lisbon

<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>Mira Point</strong><span class="small text-muted">263 Orchard Close, Lisbon</span>
  </div>
</div>

6Custom 3:2 photo

Any ratio works with the --ui-aspect-ratio variable: 2 / 3 = 66.67% for classic photo prints.

Our guide to gifts under $50 — 3:2 · Five things we learned this year

<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="Our guide to gifts under $50" class="object-cover">
  </div>
  <figcaption class="small text-muted mt-1">3:2 &middot; Five things we learned this year</figcaption>
</figure>

7Portrait team cards

A 3:4 portrait ratio (133.33%) for team photos in cards.

Amara Moreau

Backend Engineer

Mateo Fischer

Customer Success

Zoe Alvarez

Support Specialist

<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-1521335629791-ce4aec67dd15?auto=format&fit=crop&w=1200&h=800&q=70" alt="Amara Moreau" class="object-cover">
      </div>
      <div class="card-body py-2">
        <h3 class="h6 mb-0">Amara Moreau</h3>
        <p class="small text-muted mb-0">Backend 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-1601647998829-ee316a565aea?auto=format&fit=crop&w=1200&h=800&q=70" alt="Mateo Fischer" class="object-cover">
      </div>
      <div class="card-body py-2">
        <h3 class="h6 mb-0">Mateo Fischer</h3>
        <p class="small text-muted mb-0">Customer Success</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-1601647998829-ee316a565aea?auto=format&fit=crop&w=1200&h=800&q=70" alt="Zoe Alvarez" class="object-cover">
      </div>
      <div class="card-body py-2">
        <h3 class="h6 mb-0">Zoe Alvarez</h3>
        <p class="small text-muted mb-0">Support Specialist</p>
      </div>
    </div>
  </div>
</div>

8Vertical stories

A 9:16 ratio (177.78%) for phone sized stories or short clips in a scrolling row.

Omar

Ivy

Samir

Isla

<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 Omar Varga" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Omar</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 Ivy Larsen" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Ivy</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 Samir Brennan" 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 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 Isla Hughes" class="w-full h-full object-cover"><span class="absolute bottom-0 start-0 m-1 badge text-bg-dark">Isla</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:21%">
          </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:32%">
          </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:85%">
          </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:72%">
          </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:55%">
          </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:88%">
          </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:54%">
          </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:88%">
          </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.

product

What to pack for a rainy weekend outdoors

Dec 9, 2025

<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">product</span>
    <h3 class="h6">What to pack for a rainy weekend outdoors</h3>
    <p class="small text-muted mb-0">Dec 9, 2025</p>
  </div>
</div>

11Caption over a gradient

A 4:3 image with a gradient overlay so white caption text stays readable.

TorontoGift wrapping

<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">Toronto</strong><span class="small">Gift wrapping</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
	Face oil	$37.99
	Cotton throw	$87.00
	Ceramic mug	$21.99

<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-10.svg" alt="Face oil" class="object-cover"></div></td>
      <td class="align-middle">Face oil</td>
      <td class="align-middle text-end">$37.99</td>
    </tr>
    <tr>
      <td style="width:4rem"><div class="ratio ratio-1x1 rounded-md overflow-hidden"><img src="../assets/img/product-9.svg" alt="Cotton throw" class="object-cover"></div></td>
      <td class="align-middle">Cotton throw</td>
      <td class="align-middle text-end">$87.00</td>
    </tr>
    <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">$21.99</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

secondary

success

info

warning

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.

14:34New

Looking back at a busy season

2:51

How to choose the right product

12:05

What our shoppers asked us most

<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">14:34</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">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-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">2:51</span>
      </div>
    </div>
    <p class="small font-semibold mt-1 mb-0">How to choose the right product</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">12:05</span>
      </div>
    </div>
    <p class="small font-semibold mt-1 mb-0">What our shoppers asked us most</p>
  </div>
</div>

17Media list

Fixed width 4:3 thumbnails beside article titles in a reading list.

Inside our new autumn collection
Sep 6, 2026 · 10 min read
The small habits that make a big difference
Jan 28, 2026 · 5 min read
How to care for linen so it lasts for years
Feb 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="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">Inside our new autumn collection</h3><p class="small text-muted mb-0">Sep 6, 2026 &middot; 10 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">The small habits that make a big difference</h3><p class="small text-muted mb-0">Jan 28, 2026 &middot; 5 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">How to care for linen so it lasts for years</h3><p class="small text-muted mb-0">Feb 16, 2026 &middot; 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="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.

Elena

Freya

Felix

Owen

<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-11.svg" alt="Elena Kim" class="object-cover">
    </div>
    <span class="small block truncate mt-1">Elena</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="Freya Kowalski" 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-1.svg" alt="Felix Whitaker" class="object-cover">
    </div>
    <span class="small block truncate mt-1">Felix</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-10.svg" alt="Owen Novak" class="object-cover">
    </div>
    <span class="small block truncate mt-1">Owen</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>