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="d-grid gap-2 bg-body-tertiary rounded-3 p-2">
<div class="bg-primary-subtle border border-primary-subtle rounded-2 p-2 small w-25">
<code class="small">w-25</code>
</div>
<div class="bg-primary-subtle border border-primary-subtle rounded-2 p-2 small w-50">
<code class="small">w-50</code>
</div>
<div class="bg-primary-subtle border border-primary-subtle rounded-2 p-2 small w-75">
<code class="small">w-75</code>
</div>
<div class="bg-primary-subtle border border-primary-subtle rounded-2 p-2 small w-100">
<code class="small">w-100</code>
</div>
<div class="bg-primary-subtle border border-primary-subtle rounded-2 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="d-flex align-items-start gap-2 bg-body-tertiary rounded-3 p-2" style="height:160px">
<div class="bg-primary-subtle border border-primary-subtle rounded-2 p-2 small h-25">
<code class="small">h-25</code>
</div>
<div class="bg-primary-subtle border border-primary-subtle rounded-2 p-2 small h-50">
<code class="small">h-50</code>
</div>
<div class="bg-primary-subtle border border-primary-subtle rounded-2 p-2 small h-75">
<code class="small">h-75</code>
</div>
<div class="bg-primary-subtle border border-primary-subtle rounded-2 p-2 small h-100">
<code class="small">h-100</code>
</div>
<div class="bg-primary-subtle border border-primary-subtle rounded-2 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-body-tertiary rounded-3 p-2" style="max-width:22rem">
<img src="https://images.unsplash.com/photo-1714974528757-f63c72154a1b?auto=format&fit=crop&w=1600&h=700&q=70" alt="Five ways to improve your cash flow" width="900" class="mw-100 h-auto rounded-3 d-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-body-tertiary rounded-3 p-2 d-flex gap-2" style="height:120px">
<img src="https://images.unsplash.com/photo-1688380692117-63178554d76d?auto=format&fit=crop&w=800&h=800&q=70" alt="Running payroll for your first five hires" width="300" height="300" class="mh-100 w-auto rounded-3">
<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.
Tax reserve
$15.16
<div class="border rounded-3 p-3" style="max-width:20rem">
<div class="fw-semibold">
Tax reserve
</div>
<div class="small text-body-secondary mb-3">
$15.16
</div>
<button type="button" class="btn btn-primary w-100">Add to cart</button>
</div>6Progress bars with widths
Width utilities on the inner bar of a meter.
24/7 support25%
Accounting sync50%
Accounting sync75%
<div class="d-grid gap-2 small">
<div>
<div class="d-flex justify-content-between">
<span>24/7 support</span><span>25%</span>
</div>
<div class="bg-body-secondary rounded-pill" style="height:6px">
<div class="bg-danger rounded-pill h-100 w-25">
</div>
</div>
</div>
<div>
<div class="d-flex justify-content-between">
<span>Accounting sync</span><span>50%</span>
</div>
<div class="bg-body-secondary rounded-pill" style="height:6px">
<div class="bg-warning rounded-pill h-100 w-50">
</div>
</div>
</div>
<div>
<div class="d-flex justify-content-between">
<span>Accounting sync</span><span>75%</span>
</div>
<div class="bg-body-secondary rounded-pill" style="height:6px">
<div class="bg-success rounded-pill h-100 w-75">
</div>
</div>
</div>
</div>7Equal height cards
h-100 on cards inside a row makes every card as tall as the tallest.
Practical journey calm
Open a business account online in about ten minutes, with no branch visit. Accounting sync keeps your books up to date without manual exports.
We measure success by how many members come back and tell their friends.
<div class="row g-2">
<div class="col-4">
<div class="border rounded-3 p-2 h-100 small">
Practical journey calm
</div>
</div>
<div class="col-4">
<div class="border rounded-3 p-2 h-100 small">
Open a business account online in about ten minutes, with no branch visit. Accounting sync keeps your books up to date without manual exports.
</div>
</div>
<div class="col-4">
<div class="border rounded-3 p-2 h-100 small">
We measure success by how many members come back and tell their friends.
</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-100" placeholder="SAVE15">
</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="d-flex gap-2" style="height:140px">
<div class="w-25 h-100 bg-body-secondary rounded-3 p-2 small">
w-25 h-100
</div>
<div class="w-75 h-100 bg-body-tertiary border rounded-3 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="d-flex align-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-1714974528737-3e6c7e4d11af?auto=format&fit=crop&w=1200&h=800&q=70" alt="Getting paid on time: invoice tips that work" class="w-100 rounded-3">
</div>
<div class="col-6">
<img src="https://images.unsplash.com/photo-1573164574511-73c773193279?auto=format&fit=crop&w=1200&h=800&q=70" alt="How to close your books faster every month" class="w-100 rounded-3">
</div>
</div>13Half width centred
w-50 with mx-auto centres a narrow block.
w-50 mx-auto
<div class="bg-body-tertiary rounded-3 p-3">
<div class="w-50 mx-auto bg-body border rounded-3 p-2 text-center small">
w-50 mx-auto
</div>
</div>14Stat bars
Horizontal bars with width utilities compare four values.
- Omar
- Finn
- Priya
- Lea
<ul class="list-unstyled mb-0 d-grid gap-1 small">
<li class="d-flex align-items-center gap-2"><span style="width:5rem">Omar</span><span class="bg-primary rounded-1 w-100" style="height:12px"></span></li>
<li class="d-flex align-items-center gap-2"><span style="width:5rem">Finn</span><span class="bg-primary rounded-1 w-75" style="height:12px"></span></li>
<li class="d-flex align-items-center gap-2"><span style="width:5rem">Priya</span><span class="bg-primary rounded-1 w-50" style="height:12px"></span></li>
<li class="d-flex align-items-center gap-2"><span style="width:5rem">Lea</span><span class="bg-primary rounded-1 w-25" style="height:12px"></span></li>
</ul>15Vertical bar chart
h-25 to h-100 bars in a fixed height chart area.
MonTueWedThuFri
<div class="d-flex align-items-end gap-2 border-bottom px-2" style="height:140px">
<div class="bg-info rounded-top flex-fill h-50" title="Mon">
</div>
<div class="bg-info rounded-top flex-fill h-75" title="Tue">
</div>
<div class="bg-info rounded-top flex-fill h-25" title="Wed">
</div>
<div class="bg-primary rounded-top flex-fill h-100" title="Thu">
</div>
<div class="bg-info rounded-top flex-fill h-50" title="Fri">
</div>
</div>
<div class="d-flex gap-2 px-2 small text-body-secondary">
<span class="flex-fill text-center">Mon</span><span class="flex-fill text-center">Tue</span><span class="flex-fill text-center">Wed</span><span class="flex-fill text-center">Thu</span><span class="flex-fill text-center">Fri</span>
</div>16Fixed size icon tiles
Fixed inline sizes plus flex centring for square icon tiles.
<div class="d-flex gap-2">
<span class="d-inline-flex align-items-center justify-content-center text-bg-primary rounded-3" style="width:32px;height:32px"><i class="bi bi-star-fill" aria-hidden="true"></i></span> <span class="d-inline-flex align-items-center justify-content-center text-bg-primary rounded-3 fs-5" style="width:44px;height:44px"><i class="bi bi-star-fill" aria-hidden="true"></i></span> <span class="d-inline-flex align-items-center justify-content-center text-bg-primary rounded-3 fs-4" 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-content-center">
<div class="col-12 col-md-8 col-lg-6">
<label class="visually-hidden" for="ut-s-1258">Search</label>
<input id="ut-s-1258" type="search" class="form-control w-100 rounded-pill" placeholder="Find Cards">
</div>
</div>18Sidebar and content
A narrow fixed sidebar and a flex-grow-1 content area that takes the rest.
90px
flex-grow-1: Clear prices, honest advice and no surprises along the way.
<div class="d-flex border rounded-3 overflow-hidden" style="height:130px">
<div class="bg-body-secondary p-2 small flex-shrink-0" style="width:90px">
90px
</div>
<div class="flex-grow-1 p-2 small">
flex-grow-1: Clear prices, honest advice and no surprises along the way.
</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-1758518731706-be5d5230e5a5?auto=format&fit=crop&w=1600&h=700&q=70" alt="Finance tools your accountant will love" width="1600" height="700" class="w-100 h-auto rounded-4">20Width per column item
Labels with w-25 align a description list without a grid.
- Name
- Hana Larsen
- tariq.ortega@example.com
- City
- Copenhagen
<dl class="mb-0 small">
<div class="d-flex border-bottom py-1">
<dt class="w-25 fw-semibold">Name</dt>
<dd class="mb-0">Hana Larsen</dd>
</div>
<div class="d-flex border-bottom py-1">
<dt class="w-25 fw-semibold">Email</dt>
<dd class="mb-0 text-break">tariq.ortega@example.com</dd>
</div>
<div class="d-flex py-1">
<dt class="w-25 fw-semibold">City</dt>
<dd class="mb-0">Copenhagen</dd>
</div>
</dl>