What this test checks
Phones
Widths of 320, 360, 375, 390 and 414 px, where sideways scrolling hurts most.
Tablets and foldables
Widths of 672, 768, 834 and 1024 px.
Laptops and desktops
Widths of 1280 and 1440 px.
Horizontal overflow
How many pixels wider than the screen the page is at each width.
Offending elements
The outermost elements that extend past the right edge, with their CSS selector and where their right edge ends.
Sample result
A real result for devteam.co.kr, tested 17 hours ago.
Responsive layout
The layout fits all 11 tested screen widths.
Phones (320–414px) (Good)
Content fits the screen at every tested width (414px, 390px, 375px, 360px, 320px).
Fits at 5 widths
Tablets and foldables (672–1024px) (Good)
Content fits the screen at every tested width (1024px, 834px, 768px, 672px).
Fits at 4 widths
Laptops and desktops (1280–1440px) (Good)
Content fits the screen at every tested width (1440px, 1280px).
Fits at 2 widths
Screen widths tested
How it works
- The test runs in headless Chromium on our test server in Virginia, USA, in the same browser session as the accessibility check.
- After the page loads at 1366×860, the window is resized from 1440 px down to 320 px, and the layout is measured once it settles at each width.
- Overflow is the page's scroll width minus the window width, and anything over 1 px counts; fixed-position and hidden elements are ignored when finding the cause.
- Every request goes through a network guard that only connects to public IP addresses on ports 80 and 443.
How it is scored
The score uses our item-weighted formula: each screen group earns full credit when it fits, half when the worst overflow is 8 px or less and none above that, with phones weighted 3× and tablets and desktops 2× each. Grades follow our scale: A+ 95+, A 90+, B 80+, C 70+, D 60+, F below 60.
| Check | Good | Needs work | Poor |
|---|---|---|---|
| Phones (320–414 px) | No overflow | Up to 8 px | More than 8 px |
| Tablets and foldables (672–1024 px) | No overflow | Up to 8 px | More than 8 px |
| Laptops and desktops (1280–1440 px) | No overflow | Up to 8 px | More than 8 px |
Grades: A+ 95–100 · A 90–94 · B 80–89 · C 70–79 · D 60–69 · F below 60.