Album cover size
Album artwork has an unusual property: you almost never deal with the streaming services directly. A distributor sits in between, and its requirements are the ones that actually gate your release. Those requirements converge on one number.
Build at 3000 x 3000
Cover art is square, and the practical target is 3000 x 3000 pixels. That is the size the major distributors ask for, and it is large enough that every downstream service can generate its own smaller versions from it without you doing anything.
Working smaller and scaling up later does not work. Upscaling invents detail that was never there, and it is most obvious on exactly the thing cover art is full of: type edges and flat colour gradients.
The file should be RGB, not CMYK. CMYK is for print, and a CMYK file submitted as cover art either gets rejected or comes back with shifted, muted colour.
It has to work as a small square
The cover is displayed at roughly the size of a postage stamp in a queue, a search result and a lock screen. Detailed illustration, small type and thin lines all disappear at that size.
The covers that survive have one strong shape or one strong colour relationship, and either no text or very few words set large. If your artist name is set at the size it would be on a printed sleeve, it will be an unreadable smudge in a playlist.
Check it by shrinking it to about 60 pixels square and looking at it. Whatever is still legible there is your cover; everything else is decoration for the people who open the full-size view, and that is a small minority.
The content rules that get releases rejected
Distributors reject artwork for a consistent short list of reasons, and they are worth knowing before you design rather than after. Artwork that contains a website address, a social media handle, or any pricing or promotional text is routinely rejected.
Artwork that includes a logo you do not own — a streaming service logo, a label mark you are not signed to — is rejected. Blurry or pixellated artwork is rejected. Artwork whose text does not match the release title and artist name as submitted is rejected.
None of these are aesthetic judgements; they are automated or near-automated checks, and a rejection costs you days on a release schedule.
Podcast covers are the same shape but not the same rules
If you are also publishing a podcast, the square canvas is the same but the specification is stricter. Apple Podcasts accepts square artwork from 1400 x 1400 up to 3000 x 3000, in JPG or PNG, in the RGB colour space, and it rejects files that carry an alpha channel.
That last one is the trap. A PNG exported with transparency looks identical on your screen and fails validation. Exporting at the podcast size in the editor flattens the image onto an opaque background for exactly this reason.
Quick answers
What size should album artwork be?
3000 x 3000 pixels, square, RGB. That is what the major distributors ask for and it scales down cleanly to every display size.
Can I use a photo I found online?
No. Cover art needs to be work you own or have licensed. Distributors check, and a copyright claim after release is considerably worse than a rejection before it.
Does the cover need my artist name on it?
It is not required, and many covers do not have it. If you do include text, it has to match the artist and release names you submit, or the release gets rejected.