Sizing
Sizing utilities set width and height as a percentage of the parent (w-25 to w-100, h-25 to h-100, plus w-auto and h-auto), cap them with mw-100 and mh-100, or relate them to the viewport with vw-100, vh-100, min-vw-100 and min-vh-100.
1Width percentages
w-25, w-50, w-75, w-100 and w-auto relative to the parent.
w-25w-50w-75w-100w-auto<div class="grid gap-2 bg-surface-3 rounded-lg p-2">
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small w-1/4">
<code class="small">w-25</code>
</div>
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small w-1/2">
<code class="small">w-50</code>
</div>
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small w-3/4">
<code class="small">w-75</code>
</div>
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small w-full">
<code class="small">w-100</code>
</div>
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small w-auto">
<code class="small">w-auto</code>
</div>
</div>2Height percentages
h-25 to h-100 relative to a parent with a fixed height.
h-25h-50h-75h-100h-auto<div class="flex items-start gap-2 bg-surface-3 rounded-lg p-2" style="height:160px">
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small h-1/4">
<code class="small">h-25</code>
</div>
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small h-1/2">
<code class="small">h-50</code>
</div>
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small h-3/4">
<code class="small">h-75</code>
</div>
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small h-full">
<code class="small">h-100</code>
</div>
<div class="bg-primary-subtle border border-primary/30 rounded-md p-2 small h-auto">
<code class="small">h-auto</code>
</div>
</div>3Max width 100
mw-100 keeps a wide element from overflowing its parent.
mw-100 on a 900px wide image<div class="bg-surface-3 rounded-lg p-2" style="max-width:22rem">
<img src="https://images.unsplash.com/photo-1560439514-0fc9d2cd5e1b?auto=format&fit=crop&w=1600&h=700&q=70" alt="Looking back at a busy season" width="900" class="max-w-full h-auto rounded-lg block">
<div class="small mt-1">
<code>mw-100</code> on a 900px wide image
</div>
</div>4Max height 100
mh-100 limits a child to the height of its parent.
mh-100 keeps the 300px image inside the 120px box.<div class="bg-surface-3 rounded-lg p-2 flex gap-2" style="height:120px">
<img src="https://images.unsplash.com/photo-1762968269894-1d7e1ce8894e?auto=format&fit=crop&w=800&h=800&q=70" alt="Highlights from last year's workshops" width="300" height="300" class="max-h-full w-auto rounded-lg">
<div class="small">
<code>mh-100</code> keeps the 300px image inside the 120px box.
</div>
</div>5Full width button
w-100 turns a button into a block that fills its column.
Student pass
$53.91
<div class="border rounded-lg p-4" style="max-width:20rem">
<div class="font-semibold">
Student pass
</div>
<div class="small text-muted mb-4">
$53.91
</div>
<button type="button" class="btn btn-primary w-full">Add to cart</button>
</div>6Progress bars with widths
Width utilities on the inner bar of a meter.
Recorded sessions25%
Mobile agenda50%
Networking lounges75%
<div class="grid gap-2 small">
<div>
<div class="flex justify-between">
<span>Recorded sessions</span><span>25%</span>
</div>
<div class="bg-surface-2 rounded-full" style="height:6px">
<div class="bg-danger rounded-full h-full w-1/4">
</div>
</div>
</div>
<div>
<div class="flex justify-between">
<span>Mobile agenda</span><span>50%</span>
</div>
<div class="bg-surface-2 rounded-full" style="height:6px">
<div class="bg-warning rounded-full h-full w-1/2">
</div>
</div>
</div>
<div>
<div class="flex justify-between">
<span>Networking lounges</span><span>75%</span>
</div>
<div class="bg-surface-2 rounded-full" style="height:6px">
<div class="bg-success rounded-full h-full w-3/4">
</div>
</div>
</div>
</div>7Equal height cards
h-100 on cards inside a row makes every card as tall as the tallest.
Practical journey practical
Thousands of attendees already trust us, and we work hard to keep it that way. We listen first, then build a plan around what you actually need.
Every attendee receives a certificate of participation.
<div class="row g-2">
<div class="col-4">
<div class="border rounded-lg p-2 h-full small">
Practical journey practical
</div>
</div>
<div class="col-4">
<div class="border rounded-lg p-2 h-full small">
Thousands of attendees already trust us, and we work hard to keep it that way. We listen first, then build a plan around what you actually need.
</div>
</div>
<div class="col-4">
<div class="border rounded-lg p-2 h-full small">
Every attendee receives a certificate of participation.
</div>
</div>
</div>8Half width on desktop only
w-100 on phones; the grid column col-md-6 does the narrowing from md, so the form stays readable.
<div class="row">
<div class="col-md-6">
<label class="form-label" for="ut-coupon-1256">Coupon code</label>
<input id="ut-coupon-1256" type="text" class="form-control w-full" placeholder="SAVE22">
</div>
</div>9Full height split
Two panes with h-100 inside a fixed height container.
w-25 h-100
w-75 h-100
<div class="flex gap-2" style="height:140px">
<div class="w-1/4 h-full bg-surface-2 rounded-lg p-2 small">
w-25 h-100
</div>
<div class="w-3/4 h-full bg-surface-3 border rounded-lg p-2 small">
w-75 h-100
</div>
</div>10Viewport units (preview)
vw-100, vh-100, min-vw-100 and min-vh-100 size elements to the viewport; shown here as a reference table.
| Class | Sets | Typical use |
|---|---|---|
vh-100 | height: 100vh | full screen hero |
min-vh-100 | min-height: 100vh | sticky footer layout |
vw-100 | width: 100vw | edge to edge strip |
min-vw-100 | min-width: 100vw | wide canvas |
<table class="table table-sm small mb-0">
<thead>
<tr>
<th scope="col">Class</th>
<th scope="col">Sets</th>
<th scope="col">Typical use</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>vh-100</code></td>
<td>height: 100vh</td>
<td>full screen hero</td>
</tr>
<tr>
<td><code>min-vh-100</code></td>
<td>min-height: 100vh</td>
<td>sticky footer layout</td>
</tr>
<tr>
<td><code>vw-100</code></td>
<td>width: 100vw</td>
<td>edge to edge strip</td>
</tr>
<tr>
<td><code>min-vw-100</code></td>
<td>min-width: 100vw</td>
<td>wide canvas</td>
</tr>
</tbody>
</table>11Auto width in flex
w-auto lets an input shrink to its content inside a flex row.
<div class="flex items-center gap-2">
<label class="small" for="ut-rows-1257">Rows per page</label>
<select id="ut-rows-1257" class="form-select form-select-sm w-auto">
<option>10</option>
<option>25</option>
<option>50</option>
</select>
</div>12Image fills its column
w-100 on an image makes it scale to the column width.
<div class="row g-2">
<div class="col-6">
<img src="https://images.unsplash.com/photo-1769755409781-9e8924c57362?auto=format&fit=crop&w=1200&h=800&q=70" alt="Joining online: how the virtual pass works" class="w-full rounded-lg">
</div>
<div class="col-6">
<img src="https://images.unsplash.com/photo-1769798643655-e0f10f62c3fd?auto=format&fit=crop&w=1200&h=800&q=70" alt="Our favourite tips for busy weeks" class="w-full rounded-lg">
</div>
</div>13Half width centred
w-50 with mx-auto centres a narrow block.
w-50 mx-auto
<div class="bg-surface-3 rounded-lg p-4">
<div class="w-1/2 mx-auto bg-page border rounded-lg p-2 text-center small">
w-50 mx-auto
</div>
</div>14Stat bars
Horizontal bars with width utilities compare four values.
- Finn
- Mason
- Luna
- Ethan
<ul class="list-unstyled mb-0 grid gap-1 small">
<li class="flex items-center gap-2"><span style="width:5rem">Finn</span><span class="bg-primary rounded-sm w-full" style="height:12px"></span></li>
<li class="flex items-center gap-2"><span style="width:5rem">Mason</span><span class="bg-primary rounded-sm w-3/4" style="height:12px"></span></li>
<li class="flex items-center gap-2"><span style="width:5rem">Luna</span><span class="bg-primary rounded-sm w-1/2" style="height:12px"></span></li>
<li class="flex items-center gap-2"><span style="width:5rem">Ethan</span><span class="bg-primary rounded-sm w-1/4" style="height:12px"></span></li>
</ul>15Vertical bar chart
h-25 to h-100 bars in a fixed height chart area.
MonTueWedThuFri
<div class="flex items-end gap-2 border-b px-2" style="height:140px">
<div class="bg-info rounded-t-md flex-auto h-1/2" title="Mon">
</div>
<div class="bg-info rounded-t-md flex-auto h-3/4" title="Tue">
</div>
<div class="bg-info rounded-t-md flex-auto h-1/4" title="Wed">
</div>
<div class="bg-primary rounded-t-md flex-auto h-full" title="Thu">
</div>
<div class="bg-info rounded-t-md flex-auto h-1/2" title="Fri">
</div>
</div>
<div class="flex gap-2 px-2 small text-muted">
<span class="flex-auto text-center">Mon</span><span class="flex-auto text-center">Tue</span><span class="flex-auto text-center">Wed</span><span class="flex-auto text-center">Thu</span><span class="flex-auto text-center">Fri</span>
</div>16Fixed size icon tiles
Fixed inline sizes plus flex centring for square icon tiles.
<div class="flex gap-2">
<span class="inline-flex items-center justify-center text-bg-primary rounded-lg" style="width:32px;height:32px"><i class="bi bi-star-fill" aria-hidden="true"></i></span> <span class="inline-flex items-center justify-center text-bg-primary rounded-lg text-lg" style="width:44px;height:44px"><i class="bi bi-star-fill" aria-hidden="true"></i></span> <span class="inline-flex items-center justify-center text-bg-primary rounded-lg text-xl" style="width:56px;height:56px"><i class="bi bi-star-fill" aria-hidden="true"></i></span>
</div>17Search bar width
w-100 on phones and w-50 from md via a responsive column, centred with mx-auto.
<div class="row justify-center">
<div class="col-12 col-md-8 col-lg-6">
<label class="sr-only" for="ut-s-1258">Search</label>
<input id="ut-s-1258" type="search" class="form-control w-full rounded-full" placeholder="Find Keynote">
</div>
</div>18Sidebar and content
A narrow fixed sidebar and a flex-grow-1 content area that takes the rest.
90px
flex-grow-1: We measure success by how many attendees come back and tell their friends.
<div class="flex border rounded-lg overflow-hidden" style="height:130px">
<div class="bg-surface-2 p-2 small shrink-0" style="width:90px">
90px
</div>
<div class="grow p-2 small">
flex-grow-1: We measure success by how many attendees come back and tell their friends.
</div>
</div>19Responsive image height
h-auto with w-100 keeps the aspect ratio when the width changes.
<img src="https://images.unsplash.com/photo-1773829020694-413e879d2957?auto=format&fit=crop&w=1600&h=700&q=70" alt="Talks, workshops and new friendships" width="1600" height="700" class="w-full h-auto rounded-xl">20Width per column item
Labels with w-25 align a description list without a grid.
- Name
- Theo Lindqvist
- mia.tanaka@example.com
- City
- Toronto
<dl class="mb-0 small">
<div class="flex border-b py-1">
<dt class="w-1/4 font-semibold">Name</dt>
<dd class="mb-0">Theo Lindqvist</dd>
</div>
<div class="flex border-b py-1">
<dt class="w-1/4 font-semibold">Email</dt>
<dd class="mb-0 break-words">mia.tanaka@example.com</dd>
</div>
<div class="flex py-1">
<dt class="w-1/4 font-semibold">City</dt>
<dd class="mb-0">Toronto</dd>
</div>
</dl>