The Social Magnum blog
Notes from building on all social networks — the platform rules, the publishing playbooks and the API behaviour nobody documents. Every figure here was checked on a live account.
YouTube Profile Picture Size: 98 x 98 Is Not the Upload
The only dimension YouTube publishes is 98 x 98, and it is the size the picture comes out at rather than the file you should send. Upload one at that size and you get the blurry avatar people keep asking about.
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YouTube Shorts Size: A Shape, Not a Resolution
Every guide says 1080 x 1920. YouTube says square or vertical, up to three minutes, and never mentions a resolution at all. The difference decides which revenue model your upload lands in.
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Twitter Header Size: What X Actually Publishes
Canva gives two different answers on two pages that both rank for this. X gives one, calls it recommended rather than minimum, and adds a caveat about animated GIFs that no guide on page one repeats.
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Facebook Event Cover Photo Size: Which Number Has a Source?
Page one agrees on 1920 x 1005. Meta publishes 1920 x 1080. One widely-read guide prints the first number beside the second one's aspect ratio, and the arithmetic shows which of them moved.
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Instagram Auto Reply: Six Features, One Name
Six different features get called Instagram auto reply, and one of them is not automated at all. What each does, the platform rule that governs all of them, and the delivery detail that quietly undercuts comment-to-DM campaigns.
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Social Media Image Sizes: Documented, or Just Widely Agreed?
Every size guide gives you a table. This one marks which figures the platforms actually publish and which the internet simply agreed on — a distinction that decides how much to trust each number.
Read the articleWe write this down because we hit it ourselves.
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