The recommended X (Twitter) header is 1500&times;500 pixels, which is a 3:1 aspect ratio, and X accepts JPG, PNG and GIF files up to roughly 2&nbsp;MB. Uploading at that exact size avoids X re-scaling and softening your image. This tool keeps the editing canvas and the PNG export locked to 1500&times;500 via <code>canvas.toBlob</code>, so what you download matches the spec pixel-for-pixel. Because X still crops the header differently on mobile than on desktop, keep the important parts centred; the built-in guides show you where. These sizes are current best estimates &mdash; X changes them without notice, so verify on your live profile.

On desktop X paints your circular profile photo over the lower-left corner of the banner, so anything there is hidden behind the avatar. On phones the header is cropped more aggressively &mdash; roughly 50&nbsp;px is trimmed off the top and the bottom (leaving a visible area closer to 1500&times;400) and the sides can be shaved depending on screen width. X also overlays the account name and bio, and the Follow or Edit-profile button clips the lower-right. The practical rule is to keep logos and text inside the centre safe zone (about 1200&times;400) and out of the lower-left avatar circle and lower-right button area. This tool draws all four of those danger zones as toggleable overlays so you can check your layout before you export. They are guidance, not a guarantee &mdash; the exact pixels vary by device, browser and window size.

Privacy is structural. The header is drawn on an HTML canvas in your browser, and the PNG is produced locally with <code>canvas.toBlob</code> &mdash; there is no server, upload, database or logging in the processing path, and no CDN. When you add a background or layer image, the browser creates an in-memory object URL and draws straight from it; that URL is revoked automatically when you replace the image, delete the layer, reset, or leave the page, so nothing lingers in memory or on disk. The tool works offline once cached, and closing the tab discards your design. The only optional network use anywhere on the site is consent-gated advertising, which never sees your images. The safe-zone guides are drawn only in the preview and are never included in the exported file.

Because phones shrink and crop the header, thin or small text tends to disappear. A good rule is to keep any essential wording bold and roughly 40&nbsp;px or larger (in the 1500&times;500 coordinate space) and to place it inside the centre safe zone, well away from the lower-left avatar and the lower-right button. This tool&rsquo;s text layers use large default sizes, expose a font-size slider, and support weight, alignment, a drop shadow and uppercase so your text stays legible over busy backgrounds; a darken-overlay control on image backgrounds helps too. Preview with the mobile-crop guide on, then check the final PNG on a real phone &mdash; that is the only way to be sure, since X can re-compress the upload and colours may shift slightly.