Sizing in Bootstrap Utilities

<div style="width: 50%" class="border border-dark">
    <div class="bg-primary p-3 w-25">Width 25% relative to the parent</div>
    <div class="bg-primary p-3 w-50">Width 50% relative to the parent</div>
    <div class="bg-primary p-3 w-75">Width 75% relative to the parent</div>
    <div class="bg-primary p-3 w-100">Width 100% relative to the parent</div>
    <div class="bg-primary p-3">Width Auto relative to the parent</div>
    <div class="bg-primary p-3 vw-100">Width 100% relative to viewport</div>
    <div class="bg-primary p-3 min-vw-100">Min-width 100% relative to viewport</div>
</div>

References
https://getbootstrap.com/docs/4.3/utilities/sizing/