Social media image size requirements are scattered across a dozen different help pages, phrased inconsistently, and easy to get wrong. Here's the practical version — what actually matters for each platform, and the file size that clears all of them without a second thought.
Why this is confusing in the first place
Every platform enforces limits differently. Some cap file size directly, some cap it indirectly through automatic compression on upload (regardless of what you send), and some care more about pixel dimensions and aspect ratio than raw file size at all. That's why a photo that looks fine on one platform can come out blurry or get rejected on another.
The general-purpose target
If you just want one number that works almost everywhere without thinking about it further: compress to under 2-3MB. That clears the vast majority of upload limits across major platforms and is well within the range where quality loss stays effectively invisible on a normal photo.
Platform-by-platform notes
- Instagram — cares more about aspect ratio and resolution than raw file size; it also re-compresses everything on upload regardless of what you send, so starting from an already-reasonable file size (rather than a massive original) tends to give a cleaner final result.
- LinkedIn — similar story: dimension and aspect ratio matter more day-to-day than file size, but a smaller upload moves through their editor faster.
- X (Twitter) — has historically been stricter about file size for standard image posts than some other platforms; keeping images in the low single-digit megabytes avoids the platform's own compression kicking in harder than you'd like.
- Email attachments — a different category entirely, since most providers cap the whole message rather than one image. If you're attaching a photo to an email rather than posting it, our Gmail-specific guide covers that limit directly.
Getting there without guessing per platform
Rather than memorizing each platform's specific number, the simpler approach: compress once to a conservative general target, and use that same file everywhere.
- Drop your photo into the compressor and set a 2-3MB target.
- Check the preview — at that target, quality loss should be effectively invisible for normal social sharing.
- Reuse the same compressed file across platforms instead of re-processing separately for each one.
When you actually need platform-specific sizing
If you're doing something more deliberate — a carefully cropped cover photo, an ad creative with exact dimension requirements, a print-quality upload — dimension and aspect ratio matter more than file size, and that's worth checking against the specific platform's current spec rather than a general cheat sheet. This guide covers the common case: getting an ordinary photo to post without a rejected upload or a surprise quality hit.
Is a photo just not posting and you're not sure why? File size is the first thing worth ruling out — it's the most common, least visible reason an otherwise normal photo gets stuck.