How to use
- Open the page; your resolution appears at the top.
- Read the details in the table, including physical pixels and the refresh rate.
- Resize the browser window to see the viewport size change.
Options explained
- CSS pixels and physical pixels
- Browsers report sizes in CSS pixels. With display scaling, each CSS pixel covers several physical pixels; multiply by the device pixel ratio to get the panel's native resolution.
- Refresh rate
- Estimated from how often the browser draws frames over about a second. Power-saving modes and some browsers cap it at 60 Hz even on faster screens.
Scaling examples and how the values are derived
The row “Physical pixels” is Screen size (CSS pixels) multiplied by the Device pixel ratio, each rounded to a whole number. Typical combinations:
| Panel (physical) | Display scaling | Screen size (CSS pixels) | Device pixel ratio |
|---|---|---|---|
| 1920 × 1080 | 100% | 1920 × 1080 | 1 |
| 2560 × 1440 | 100% | 2560 × 1440 | 1 |
| 3840 × 2160 | 150% | 2560 × 1440 | 1.5 |
| 3840 × 2160 | 200% | 1920 × 1080 | 2 |
The ratio in brackets after the screen size, such as 16:9, is the width and height reduced by their greatest common divisor. If that does not give small whole numbers, the closest common ratio is shown with a leading ≈ sign, so 2560 × 1080 appears as ≈ 21:9. A 1440 × 900 screen is written 16:10 rather than 8:5, by convention.
Browser window (viewport) is the size of the page area and changes as you resize the window, while Screen size and Available screen area, which excludes taskbars and docks, stay the same.
The Refresh rate (measured) comes from the time between about 90 animation frames. The tool takes the median gap and converts it to hertz, then snaps to a standard rate (24, 30, 48, 50, 60, 72, 75, 90, 100, 120, 144, 165, 170, 180, 240 or 360 Hz) when it is within 3% of one; otherwise it shows the rounded value.
Frequently asked questions
Why is my resolution lower than the monitor's spec?
Display scaling is on. A 4K monitor at 150% scaling reports 2560 × 1440 CSS pixels with a pixel ratio of 1.5.
Why does the refresh rate show 60 Hz on my 144 Hz monitor?
Check the refresh rate in your display settings, and make sure the browser window is on that monitor. Battery saver modes can also limit it.
Which screen is measured with several monitors?
The one the browser window is on.
Privacy
This tool runs entirely in your browser. Your files and text are processed on your device and are never uploaded to our servers.