YouTube banner size and the safe area
The channel banner is the one YouTube asset where the recommended size and the visible size are completely different numbers, and that catches almost everybody. You upload a wide image, it looks right on a computer, and on a phone half of it is gone.
The two numbers that matter
YouTube's own documentation gives a recommended upload size of 2560 x 1440 pixels for channel art, with a file size limit of 6 MB.
But that whole canvas is never shown at once. The area guaranteed to be visible on every device — phone, tablet, desktop and television — is the central 1546 x 423 pixels. That is the safe area, and it is where your name, your tagline and your logo have to live.
Everything outside that central strip is decoration that some viewers will see and others will not. Treat it as background, never as information.
Why one image gets cropped four ways
A television shows the full 2560 x 1440. A desktop browser shows a wide, short slice of it. A tablet shows something in between. A phone shows only the central strip.
So the design has to work as a set of nested rectangles: the safe strip has to read on its own, and each larger crop has to look deliberate rather than like the safe strip with random edges attached.
The practical consequence is that a banner built around a single centred block of text and a simple background works everywhere, and a banner built as a wide collage works only on the one screen you designed it on.
Designing inside the safe area
Put the channel name in the middle, sized so it reads at the small end. Keep any tagline short and directly under it. If you use a logo, put it beside or above the name, still inside the strip.
The strip is very wide and very short — a 3.65:1 ratio. That shape punishes tall stacked layouts. One line, or two short lines, is what fits.
Leave the outer area as texture, gradient or a continuation of your background colour. If you want an illustration out there, make sure it never carries meaning that the phone viewer would miss.
What to check before you upload
Shrink the safe strip mentally to the size it appears on a phone and see whether the name is still legible. Channel names get set far too small more often than too large.
Check the contrast between your text and the background behind it, not the background in general. A name that sits half on a light area and half on a dark one is unreadable on both halves.
Avoid putting anything important in the bottom right of the desktop crop — YouTube overlays social links and other interface elements around the banner edges depending on the surface.
Making one in the editor
Set a custom canvas of 2560 x 1440, build your background, and keep the type centred. Because the editor works in proportional coordinates, a design centred in the frame stays centred at every export size, which is exactly what a banner needs.
Export as PNG if the banner is flat colour and type, JPG if it is photographic and you want to stay comfortably under the 6 MB ceiling.
Quick answers
What is the exact safe area?
1546 x 423 pixels, centred in the 2560 x 1440 canvas. That rectangle is visible on every device; everything outside it may be cropped.
Can I upload a smaller image?
You can, but it will be scaled up to fill the canvas and will look soft on televisions and high-density screens. Building at the full 2560 x 1440 costs nothing.
Does the banner affect search?
Not directly. It affects whether someone who has clicked through to your channel stays, which is a different and also useful thing.