# Social media image size checker: dimensions, weight and formats

> Markdown version of https://postlake.dev/tools/image-checker . The canonical page for humans.
> PostLake is the social media API for AI agents: https://postlake.dev/llms.txt
> Every number below is generated from the registry PostLake's publish path
> validates against, so it cannot state a limit the API would not enforce.

A free browser tool that reads an image's real dimensions, weight and format
and tells you which social networks will accept it. Where a network refuses
it, one click produces a version that network accepts: resized inside its
bounds, converted to a format it takes and compressed under its weight cap.
All of it happens on a canvas in the page, so the image is never uploaded.

Use it at https://postlake.dev/tools/image-checker

## Image rules by network

| Network | Images per post | Formats | Max weight | Pixel bounds |
|---|---|---|---|---|
| TikTok | 35 | JPEG, WEBP | 20MB | 540x960 to 1080x1920 |
| Instagram | 10 | JPEG | 8MB | no stated bounds |
| X | 4 | JPEG, PNG, WEBP, GIF | 5MB | no stated bounds |
| LinkedIn | 20 | JPEG, PNG, GIF | 8MB | no stated bounds |
| Facebook | 10 | JPEG, PNG, GIF, WEBP | 10MB | no stated bounds |
| Threads | 20 | JPEG, PNG | 8MB | no stated bounds |
| Bluesky | 4 | JPEG, PNG, WEBP, GIF | 1MB | no stated bounds |
| Pinterest | 5 | JPEG, PNG | 20MB | no stated bounds |

## The three things that get an image rejected

**Pixels.** TikTok caps photo posts at 1080x1920 and requires at least
540x960. The ceiling is smaller than most phone cameras produce, so an
untouched camera roll image fails. TikTok is the only network publishing hard
bounds, which is why that column is mostly empty above.

**Weight.** This is the real constraint everywhere else. The caps run from 1MB
on Bluesky to 20MB on Pinterest and TikTok, so a single full-resolution photo
can pass on six networks and fail on the seventh.

**Format.** TikTok accepts JPEG and WebP and rejects PNG outright. Since a
screenshot is a PNG, this is the single most common surprise.

## Video rules by network

| Network | Formats | Max weight | Max length | Video required |
|---|---|---|---|---|
| TikTok | MP4, QUICKTIME, WEBM | 4GB | 10 minutes | no |
| Instagram | MP4, QUICKTIME | 300MB | 15 minutes | no |
| X | MP4 | 512MB | 2 minutes | no |
| Facebook | MP4, QUICKTIME | 1GB | 4 hours | no |
| Threads | MP4, QUICKTIME | 1GB | 5 minutes | no |
| Bluesky | MP4 | 50MB | 1 minutes | no |
| YouTube | MP4, QUICKTIME, WEBM | 2GB | no stated cap | yes, video only |
| Pinterest | MP4 | 2GB | 15 minutes | no |

## Doing this in code instead

PostLake checks dimensions, weight and format against each target network
before publishing, so an image that a network would reject minutes after
upload is refused up front instead. Docs: https://docs.postlake.dev/quickstart

---

Free tools, no signup: https://postlake.dev/tools/ · Plain markdown for agents: https://postlake.dev/llms.txt
Canonical page: https://postlake.dev/tools/image-checker