The aspect ratio you choose directly shapes how a subject is framed, how much environment is included, and what the viewer's eye does first. Most beginners leave it at 1:1. That's leaving creative control on the table.
The Core Ratios and Their Uses
- 1:1 — Square. Instagram feed, product shots, avatars. Balanced, neutral energy.
- 4:3 — Classic photography. Natural, documentary feel.
- 3:2 — Standard camera sensor. Editorial, realistic photography aesthetic.
- 16:9 — Cinematic/widescreen. Landscapes, desktop wallpapers, YouTube thumbnails.
- 2:3 / 3:4 — Portrait orientation. Fashion, editorial, book covers, Pinterest.
- 9:16 — Mobile/vertical. Instagram Reels, TikTok, Stories.
- 21:9 — Ultra-wide cinematic. Epic landscapes, film screenshots.
How Ratio Affects Composition
A portrait at --ar 2:3 naturally isolates the subject with negative space above or below. The same portrait at --ar 16:9 forces the AI to include environment, which changes the entire feel of the image.
For Midjourney specifically: --ar 2:3 reliably produces the best portrait results. The model seems trained on more portrait photography at this ratio.
Platform Limits
Not all models support all ratios. Midjourney supports any ratio up to 2:1 or 1:2. DALL·E 3 supports 1:1, 7:4, and 4:7. Flux supports arbitrary ratios up to 1.5:1. Always check your platform's documentation.
