Borrowing it
Nothing to install: this file belongs to Branding5/social-media-image-sizes. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/Branding5/social-media-image-sizes/main/AGENTS.mdgit clone --depth 1 https://github.com/Branding5/social-media-image-sizesWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/branding5/social-media-image-sizes/agents-md)<a href="https://agentmods.dev/instructions/branding5/social-media-image-sizes/agents-md"><img src="https://agentmods.dev/badge/instructions/branding5/social-media-image-sizes/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/branding5/social-media-image-sizes/agents-md"><img src="https://agentmods.dev/badge/instructions/branding5/social-media-image-sizes/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.04369 | $0.04369 |
| Opus 5.5 | $0.01748 | $0.01748 |
| Sonnet 5.5 | $0.00874 | $0.00874 |
| Haiku 4.5 | $0.00437 | $0.00437 |
Grade A, and why
social-media-image-sizes AGENTS.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 370 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Social Media Image Sizes — 2025 Complete Reference
Version 1.0.0 | Branding5 | 2025
This document is the full compiled reference for the
social-media-image-sizesskill. It is optimised for agents and LLMs that need all platform specs in a single context window. The interactive version lives at branding5.com/tools/social-media-cheat-sheet.
Table of Contents
- X (Twitter)
- TikTok
- YouTube
- Snapchat
- Threads
- Best Practices
- Quick-Reference Table
1. Instagram
1.1 Profile
| Name | Width | Height | Aspect | Notes |
|---|---|---|---|---|
| Profile Photo | 320 | 320 | 1:1 | Displays as 110×110 on mobile |
1.2 Feed Posts
| Name | Width | Height | Aspect | Max File | Notes |
|---|---|---|---|---|---|
| Portrait Post | 1080 | 1350 | 4:5 | 30 MB | ✅ Best engagement |
| Square Post | 1080 | 1080 | 1:1 | 30 MB | |
| Landscape Post | 1080 | 566 | 1.91:1 | 30 MB |
1.3 Stories & Reels
| Name | Width | Height | Aspect | Notes |
|---|---|---|---|---|
| Story | 1080 | 1920 | 9:16 | Safe zone: center 1080×1420 |
| Reel | 1080 | 1920 | 9:16 | Cover photo: 1080×1920 |
| Reel Cover Thumbnail | 420 | 654 | 1:1.55 | Shown in grid as 1:1 crop |
1.4 Carousel Posts
| Name | Width | Height | Aspect | Notes |
|---|---|---|---|---|
| Carousel Square | 1080 | 1080 | 1:1 | Up to 10 slides |
| Carousel Portrait | 1080 | 1350 | 4:5 | Up to 10 slides; best engagement |
All slides must share the same aspect ratio. The first image sets the ratio.
1.5 Ads
| Name | Width | Height | Aspect |
|---|---|---|---|
| Feed Ad (Square) | 1080 | 1080 | 1:1 |
| Feed Ad (Landscape) | 1200 | 628 | 1.91:1 |
| Story Ad | 1080 | 1920 | 9:16 |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2mo ago First seen · 370 lines · 4,369 tokens per session scan A f84f167bbe24
social-media-image-sizes AGENTS.md is an instructions file published in the GitHub repository Branding5/social-media-image-sizes (7 stars, last pushed 6mo ago), licensed MIT. It adds 4,369 tokens to every session, about $0.0175 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
social-media-image-sizes AGENTS.md compared with instructions from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| social-media-image-sizes AGENTS.mdBranding5/social-media-image-sizes | Instructions file | 7 | 6mo ago | MIT | A | 4,369 | Codex, OpenCode |
| vscode buildNext.instructions.mdmicrosoft/vscode | Instructions file | 195k | today | MIT | A | 9,719 | GitHub Copilot |
| vscode oss-third-party-notices.instructions.mdmicrosoft/vscode | Instructions file | 195k | today | MIT | A | 5,516 | GitHub Copilot |
| next.js AGENTS.mdvercel/next.js | Instructions file | 143k | today | MIT | A | 7,461 | Codex, OpenCode |
| langchain AGENTS.mdlangchain-ai/langchain | Instructions file | 149k | today | MIT | A | 4,680 | Codex, OpenCode |
| vscode copilot-instructions.mdmicrosoft/vscode | Instructions file | 195k | today | MIT | A | 3,093 | GitHub Copilot |
| vscode model-prompts.instructions.mdmicrosoft/vscode | Instructions file | 195k | today | MIT | A | 2,022 | GitHub Copilot |