AI Image Size Guide
Pick where your photo is going and get the right size — plus the exact words or flag that make ChatGPT, Gemini, Midjourney and Flux create it in that shape.
Instagram · Feed post (portrait)
1080 × 1350
Aspect ratio 4:5
Takes the most space in the feed — best for portraits.
- ChatGPT
- Make it a portrait (vertical) image (1024×1536) — then resize or crop to 1080×1350
- Gemini
- Aspect ratio 4:5
- Midjourney
- --ar 4:5
- Flux
- width 912, height 1152
Aspect ratio calculator
Have a custom size? Enter it to get the ratio and each model's setting.
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Ratio 4:5
- ChatGPT
- Make it a portrait (vertical) image (1024×1536) — then resize or crop to 1080×1350
- Gemini
- Aspect ratio 4:5
- Midjourney
- --ar 4:5
- Flux
- width 912, height 1152
All sizes at a glance
| Platform | Use | Size (px) | Ratio | Midjourney |
|---|---|---|---|---|
| Feed post (portrait) | 1080×1350 | 4:5 | --ar 4:5 | |
| Feed post (3:4, matches profile grid) | 1080×1440 | 3:4 | --ar 3:4 | |
| Feed post (square) | 1080×1080 | 1:1 | --ar 1:1 | |
| Story / Reel | 1080×1920 | 9:16 | --ar 9:16 | |
| Profile photo | 320×320 | 1:1 | --ar 1:1 | |
| YouTube | Video thumbnail | 1280×720 | 16:9 | --ar 16:9 |
| YouTube | Channel banner | 2560×1440 | 16:9 | --ar 16:9 |
| YouTube | Shorts | 1080×1920 | 9:16 | --ar 9:16 |
| Status | 1080×1920 | 9:16 | --ar 9:16 | |
| Profile photo (DP) | 640×640 | 1:1 | --ar 1:1 | |
| Feed post | 1080×1350 | 4:5 | --ar 4:5 | |
| Page / profile cover | 851×315 | 2.7:1 | --ar 3:1 | |
| Story | 1080×1920 | 9:16 | --ar 9:16 | |
| Feed image | 1200×627 | 1.91:1 | --ar 2:1 | |
| Profile banner | 1584×396 | 4:1 | --ar 4:1 | |
| X (Twitter) | Post image | 1600×900 | 16:9 | --ar 16:9 |
| X (Twitter) | Header | 1500×500 | 3:1 | --ar 3:1 |
| Standard pin | 1000×1500 | 2:3 | --ar 2:3 | |
| Threads | Post image | 1080×1350 | 4:5 | --ar 4:5 |
| A4 poster at 300 DPI | 2480×3508 | 1:1.41 | --ar 2:3 | |
| 5×7 inch invitation at 300 DPI | 1500×2100 | 5:7 | --ar 5:7 |
Recommended upload sizes. Platforms resize anything close to these; larger images at the same ratio also work.
Frequently asked questions
- What size should an AI photo be for Instagram?
- For feed posts use 1080×1350 (4:5) — it fills the most screen. Use 1080×1920 (9:16) for Stories and Reels and 1080×1080 for square posts. In Gemini ask for aspect ratio 4:5; in Midjourney add --ar 4:5.
- How do I make ChatGPT create a vertical image?
- Add “make it a portrait (vertical) image, 1024×1536” to your prompt. ChatGPT creates square, landscape (1536×1024) and portrait (1024×1536) images; resize or crop afterwards for exact platform sizes like 1080×1920.
- What aspect ratios does Gemini support?
- Gemini's image model accepts 1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9 and 21:9. Write the ratio in your prompt, for example “aspect ratio 9:16”.
- What is the best size for a YouTube thumbnail?
- 1280×720 pixels (16:9), under 2 MB. In Midjourney use --ar 16:9; in ChatGPT ask for a landscape image and crop it to 16:9.