Bluesky post image size
1200 × 675px
Aspect ratio
16:9
Use 1200 × 675 px (16:9) as your Bluesky default — images are capped near 1 MB and downscaled to 2,000 px on the long side.
Last verified June 2026
Bluesky’s image pipeline has one constraint that shapes everything else: a file-size cap of roughly 1 MB per image (976.56 KB, precisely), with the client compressing or downscaling anything bigger — and a 2,000 px ceiling on the long side. A 1200 × 675 px (16:9) export fits comfortably under the cap, displays cleanly in the timeline, and matches the link-card shape, making it the sensible house default for designed graphics.
| Variant | Dimensions | Ratio |
|---|---|---|
| Landscape (recommended) | 1200 × 675 pxClean timeline display; comfortably under the file cap. | 16:9 |
| Maximum stored size | 2000 × 2000 pxLongest side is capped at 2,000 px; larger uploads are downscaled. | — |
| Square | 1080 × 1080 px | 1:1 |
| Portrait | 1080 × 1350 pxDisplays fine as a single image; multi-image grids crop toward square tiles. | 4:5 |
| Link card image | 1200 × 627 pxWhat Bluesky pulls from a shared URL’s social meta tags. | ~1.91:1 |
Single images display at close to their native ratio, but posts with 2–4 images switch to a grid that crops each picture toward a uniform tile — edges and extreme top/bottom go first. If a graphic will ever ship in a multi-image post, keep its message in the central square. And because compression to ~1 MB is non-negotiable, avoid fine textures and tiny type that JPEG artifacts will chew up.
Letting Bluesky’s client crunch a 5 MB PNG down to 976 KB hands quality decisions to an automatic compressor. Export deliberately instead: resize to 2,000 px or less on the long side, then save as JPEG around 80% quality or WebP — designed graphics with flat colors usually land well under 1 MB with no visible loss. What you upload is then what people see.
Bluesky’s community treats image descriptions as table stakes — many users won’t repost images without them, and the composer supports alt text on every upload. Two honest sentences describing the image content travel further than any hashtag. It’s also simply good practice that the rest of your platforms benefit from too.
Four product shots posted together become four cropped tiles, not four full images. If each picture matters individually, post them as a short self-reply chain instead of one multi-image post — threads are native behavior on Bluesky, and each reply carries its image at full display ratio.
1200 × 675 px (16:9) is the safe default for designed graphics. Bluesky stores up to 2,000 px on the long side, so photos can go larger — just keep each file near or under 1 MB.
The AT Protocol caps image blobs at 976.56 KB, and the client compresses anything bigger. Exporting under the cap yourself (resize, then JPEG/WebP at sensible quality) keeps that compression under your control.
Up to 4 per post, alongside up to 300 characters of text. Note that 2–4 images display as a cropped grid — post images individually in a thread if each one needs full framing.
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