Most short-form content is judged in under a second. Someone is scrolling a feed on a phone, your thumbnail is a small vertical rectangle surrounded by other small vertical rectangles, and they decide whether to stop almost instantly. If your headline, hook, or key visual is too small, too cropped, or hidden under the platform's interface, you lose that second. This guide explains the handful of things that actually matter before you post, and why the Would Anyone Read This? tool checks them.
The first thing is shape. Instagram Reels, TikTok, Facebook Reels, and YouTube Shorts all favour a vertical 9:16 frame. A landscape or square image gets cropped to fit, and the crop is rarely where you would choose it. Important text near the top, bottom, or sides is the first thing to disappear. Designing inside a 9:16 canvas from the start means what you make is what viewers see.
The second thing is safe zones. Every platform draws its own interface on top of your content: a top bar, a caption area, an action rail of like, comment, and share buttons down the right edge, and on YouTube Shorts a title and channel block at the bottom. Text that lands in those zones is covered. A good rule of thumb is to keep your headline and your main subject inside the centre two-thirds of the frame, and treat the outer strip as a margin, not a canvas.
The third thing is legibility at size. Text that looks fine on your laptop is often unreadable when it is 150 pixels wide and scrolling past at speed. Large, high-contrast text survives; thin, low-contrast text does not. As a rough guide, if your headline is not at least a tenth of the image height, most people on a phone will not read it.
The fourth thing is density. A frame packed with text, logos, and detail feels busy and hard to parse in the moment a viewer is deciding whether to stop. One clear focal point and one short, readable headline almost always outperform a frame that tries to say everything at once. The Would Anyone Read This? score reflects all four of these, and the platform-specific notes below show where each platform's interface tends to cover content.
Facebook Reels display vertical 9:16 with a top identity bar and a bottom caption and reaction row. Like other Reels formats, the centre of the frame is the safest place for text and the main subject.
Safe zones: Keep text out of the top ~8%, the right ~16% reaction rail, and the bottom ~14% caption strip.
Instagram Reels and Stories fill a vertical 9:16 frame. The feed crops to fit, so design edge-to-edge inside 9:16 from the start. Keep your headline large and centred, because the top bar and bottom caption area will cover anything placed there.
Safe zones: Keep clear of the top ~9% (story bar), the bottom ~14% (caption and action bar), and the right ~18% (like, comment, share rail).
TikTok plays full-screen vertical 9:16. The For You feed overlays a right-hand action rail and a bottom caption plus music ticker, so content pushed to the edges gets hidden. Bold, centred hooks read best because the eye lands in the middle of the frame.
Safe zones: Avoid the top ~7%, the right ~16% rail (profile, like, comment, share), and the bottom-left caption area (~14%).
YouTube Shorts are vertical 9:16. The Shorts player overlays a title, channel name, and subscribe button across the bottom, plus an action rail on the right. Because the bottom block is large, titles and lower-third text placed by the creator often collide with it.
Safe zones: Avoid the bottom ~22% (title and channel block), the right ~16% action rail, and the top-right corner.