What Screen Resolution Simulator does
Screen Resolution Simulator loads the entered HTTP or HTTPS URL directly in your browser inside an iframe. You can choose presets for 390×844, 768×1024, 1366×768, or 1440×900 CSS pixels, or enter a bounded custom width and height.
The frame measures layout space, not a complete device profile. It does not change the browser user agent, touch capabilities, hardware, network, pixel density, operating system, or rendering engine. Sites can also refuse embedding through X-Frame-Options or Content-Security-Policy, and PagesTools does not bypass those protections.
How to use Screen Resolution Simulator
- Enter an HTTP or HTTPS page URL.
- Choose a preset or enter a width from 240–3840 and height from 240–2160 CSS pixels.
- Select Load preview to open the page in the fixed iframe.
- Check layout changes, then verify important behavior with real browsers and devices.
Important details
CSS pixels are not hardware pixels
The selected width and height control iframe layout dimensions. They do not emulate a device's physical screen, pixel ratio, browser chrome, safe areas, or zoom behavior.
The target controls whether framing works
A page can block third-party framing with response headers. A blank or refused frame can therefore be expected security behavior rather than a PagesTools rendering error.
The iframe receives limited permissions
Scripts may run inside the sandboxed target frame, but the frame does not receive same-origin privileges from PagesTools. A no-referrer policy prevents the PagesTools page URL from being sent as the referrer.
Practical uses
- Check whether a public layout changes at common responsive widths.
- Reproduce an overflow report at a specific CSS viewport size.
- Demonstrate breakpoint behavior during a design or content review.
Privacy and limitations
The target page loads directly from your browser, so its servers and embedded resources can see normal connection data such as your public IP. PagesTools sets no-referrer on the iframe but cannot control the target's own logging or third-party resources.
This is an iframe-size check, not device emulation. Framing headers may block the page, authentication can differ, and the tool does not reproduce a mobile user agent, touch input, performance, hardware, browser chrome, or pixel density.