Quick answer
What Viewport Size Checker tells you
Track the current layout viewport and compare it with the reported screen size and device pixel ratio.
- Observed here
- Live viewport width and height, Screen size, Device pixel ratio.
- How to interpret it
- Viewport width and height describe the page content area in CSS pixels. Browser chrome, zoom and window size make these different from full-screen dimensions.
- Important limit
- Results reflect events and values exposed by this browser.
- Data handling
- Test values are calculated in this browser. Device Test Bench does not store a test result or create a device fingerprint.
Useful next comparison: Resize the window or change zoom one step at a time and compare viewport dimensions separately from screen dimensions.
Understanding the result
What a result means
The viewport is the layout area available to the page, not the full panel size. Browser chrome, zoom, scrollbars, orientation and an on-screen keyboard can all change it while screen dimensions remain the same.
Confirm the pattern by repeating live viewport width and height. Results reflect events and values exposed by this browser.
How to use this test
- Read the privacy and compatibility notes.
- Start the test and interact only inside the marked test area.
- Repeat the action several times and compare the live indicators.
- Use the troubleshooting section before deciding that hardware is faulty.
What this test checks
- Live viewport width and height
- Screen size
- Device pixel ratio
- Orientation
What this test cannot check
Results reflect events and values exposed by this browser.
This test does not certify hardware or replace professional inspection.
Mobile browser chrome and zoom can change viewport values.
Common problems and troubleshooting
Reset zoom, resize slowly and compare portrait and landscape values. On mobile, repeat with the address bar expanded and collapsed so responsive-layout behavior is not mistaken for unstable screen resolution.
- Repeat the same observation. Focus the test surface and repeat “Live viewport width and height” three times under the same conditions.
- Change one condition. Compare “Screen size” after changing only the relevant port, connection, browser setting or application.
- Rule out focus or interception. Close overlays and reserved shortcuts, keep the page visible and confirm that the live indicator changes during the action.
- Keep the result within its limit. Results reflect events and values exposed by this browser.
If the same pattern remains across relevant applications and connections, give the manufacturer or a qualified technician the repeatable observations instead of a guessed fault label.
Browser compatibility
innerWidth and innerHeight are widely supported, but mobile visual and layout viewports can differ. This tool reports the layout viewport and clearly separates it from the Screen interface.
| Browser | Reference status | Evidence basis | Version | Notes | Checked |
|---|---|---|---|---|---|
| Chrome | Supported | Expected baseline | Not recorded | Feature detection is authoritative; permissions, platform and device support can change availability. | 2026-08-27 |
| Microsoft Edge | Supported | Expected baseline | Not recorded | Feature detection is authoritative; permissions, platform and device support can change availability. | 2026-08-27 |
| Firefox | Partial | Expected baseline | Not recorded | Feature detection is authoritative; permissions, platform and device support can change availability. | 2026-08-27 |
| Safari | Partial | Expected baseline | Not recorded | Feature detection is authoritative; permissions, platform and device support can change availability. | 2026-08-27 |
Privacy information
Test values are calculated in this browser. Device Test Bench does not store a test result or create a device fingerprint.
The public analytics allowlist does not accept pressed keys, typed text, pointer coordinates, media labels, device IDs, recordings, video frames or controller input. Test results are not written to LocalStorage.
Primary technical references
These specifications define the browser signals used by this test. They document web-platform behavior; they do not certify a particular device.
Frequently asked questions
Is this Viewport Size Checker free?
Yes. The test works without an account, download or payment.
Is my test data uploaded?
Test values are calculated in this browser. Device Test Bench does not store a test result or create a device fingerprint.
Does this result prove my hardware is faulty?
No. It shows what the browser can observe. Repeat the test, compare another browser or device, and seek qualified support when the result matters.