How we check social media sizes and ad specs
Image sizes change quietly. A platform updates its help page, and old numbers keep circulating for years on pages that copy each other. Every size in this series comes from the platform's own documentation, with the date we checked it.
What counts as a source
- Allowed: the platform's own help centre, business or ads help centre, ads guide, creator or developer documentation, and official blog.
- Never used: design-tool blogs, scheduling-tool blogs, agency roundups, other "social media sizes" pages, and user-written posts that happen to sit on a platform's domain. We keep a blocklist of the ones we meet.
- Every source address must match an allowlist of official domains before a spec can publish.
Required, recommended, maximum and derived
- Required means the platform rejects or degrades anything that doesn't meet it, such as a minimum size.
- Recommended is the size the platform suggests for the best result. It is advice, not a rule, and we never present it as one.
- Maximum is the largest size, ratio, length or file the platform accepts.
- Derived marks a pixel size we worked out from an official ratio when the platform gives no pixel size. We show the arithmetic next to it and never present it as official. Where a platform publishes neither, the table says "Not published".
How verification works
Each spec is stored as a record with its source page, a short verbatim excerpt (25 words or fewer) and the date. A script fetches the source page, falling back to a real browser for pages that need JavaScript, and checks that every excerpt still appears on it. A spec only renders if it passes. The excerpts are evidence and never appear on the page.
A quality gate also checks that every number on a record appears in its own excerpts, that sizes match their stated ratio, that minimums are not above the recommended size, and that the short answer and FAQs use only verified numbers.
How often pages are checked
Every platform is re-checked monthly, and a weekly job reports any source that has moved or changed. When a spec changes, we add a new record with the new values and the date, and keep the old one under "What changed" on the page. Published anchors never change, so links to a spec keep working.
What we leave out
If a platform's own pages don't state a size, we don't publish one, even when the figure is widely quoted. Each platform page says where a common size is not official. A missing row is better than a wrong one.
Report an error
If a platform's documentation says something different from a page here, send us the link and we will re-check it. Written and maintained by Muhammed Abdul Kalam.