X header size and safe area

What a header is for

Unlike a post, a header is not in anyone's feed. It is seen by people who have already chosen to look at a profile, usually after a post, a reply or a mention caught their attention. That makes it a place for context rather than persuasion: what the account is, what it is currently promoting, or simply a mood that matches the brand. Because the same image may sit there for months, it also works as a noticeboard for something with a date, like a launch, a series or an event, provided someone remembers to change it when the date has passed.

Working with a three to one shape

A 1500 by 500 image is exactly three times as wide as it is tall. Aspect ratio, written in CSS as width divided by height, is what a browser keeps constant when it scales a box to fit a column, so on a wide monitor the header is shown large and on a phone the same shape becomes a slim strip only a few centimetres tall. Some layouts also fit the image into a box with slightly different proportions, which trims the top and bottom. The consequence is that nothing near the edges is guaranteed, and a single line of text in the middle has to carry the whole message at a small physical size.

The profile photo and the layout around it

Buffer's current guide gives the X profile photo as 400 by 400 pixels at upload. On the profile page it is shown as a circle overlapping the lower left of the header, and the display name, handle, bio and follow button sit below. That overlap is the single most common reason a header design fails: a logo or a date placed in the bottom left corner ends up behind someone's face. The follow or edit button sits below the right hand side of the header rather than on it, so the right side is safer than the left, but still exposed to trimming on narrow screens.

When it matters

Headers earn attention at particular moments. An account that is quoted or mentioned widely gets a surge of profile visits, and the header is what those visitors see. A company launching a product, a speaker announcing a talk, or a charity running an appeal can use that space for a few weeks at no cost. The header also appears, reduced, in the hover card shown when someone points at a name on the web, so a bold, simple design keeps working at that small size too. A busy photograph with fine text does not.

Common mistakes

Putting the logo or a call to action in the lower left, under the profile photo. Running a slogan edge to edge so phones trim both ends. Setting type small enough to read on a laptop but illegible on a phone, where the header may be barely three centimetres tall. Reusing a 1200 by 628 ad image, which is a different shape and gets heavily cropped. Choosing a header in the same colour as the profile photo, so the circle disappears into the background. And leaving an expired event date in place long after the event.

The Twitter Header canvas in the flyer builder

The flyer builder still names this canvas Twitter Header, set at 1500 by 500 pixels, and each of the 199 designs is authored natively for it rather than stretched from another shape. PNG and JPG exports capture at twice the canvas, so the file leaves at 3000 by 1000 pixels. Switching a flyer to this size from, say, a Facebook Cover swaps in the design's header layout and carries content across by slot, with style changes stored for this size alone. There are no guides, snapping or safe area overlays in the builder, so keeping the lower left and the edges clear is a judgement made by eye.

Questions people ask