Responsive Viewport Sizes
A practical viewport size reference for testing mobile, tablet, and desktop layouts before release.
5 min read - Updated 2026-05-13
Use this guide as a compact release reference, then validate the same breakpoints in Sizzy with synchronized devices and screenshot evidence.
Use ranges before presets
Device presets are useful for proof, but viewport ranges catch the messy handoff points where layouts actually break. Start narrow, widen gradually, and log the exact width where each layout shift happens.
320-389px for compact phones
390-479px for modern phones
480-767px for large phones and small tablets
768-1199px for tablet and small desktop handoff
Add product-specific widths
Analytics and product surfaces should shape the final QA matrix. Dashboards, pricing pages, checkout flows, and embedded tools often need extra widths beyond the default responsive set.
Add 1024px when sidebars or tables are important
Add 1366px for common laptop review
Add height variants when sticky CTAs are present
Add the minimum supported width to release notes
Release checklist
Test one width inside every major responsive range.
Check 20px before and after important CSS breakpoints.
Capture release screenshots using the same viewport matrix.
Retest with realistic copy, validation states, and authenticated UI.
Benji
Your life OS
The companion app that keeps every area of your world in sync.
Zero to Shipped
Ship products, not side projects
The ultimate Next.js boilerplate for building and launching real products.
DMX
Mindful Twitter/X
The intentional X client for macOS. Reclaim your attention span.
Sotto
Voice-to-text for macOS
Speak naturally. Type instantly. 100% local & private.
Passlock
Password manager with willpower
Lock passwords with time delays, word challenges, or hand the keys to someone you trust.
Glink
Changelogs that slap
Beautiful changelogs and roadmaps for your product.
JoinRepo
GitHub access control
Monetize your GitHub repositories with ease.
Tubely
YouTube Studio for Mac
Manage multiple YouTube channels in one native app.
JustWrite
Distraction-free writing
A minimal writing app that helps you focus on what matters.