AI Image Generators Aspect Ratios & Image Sizes
Master aspect ratios and resolution buckets in AI image generation. Learn how to configure Midjourney --ar flags, understand DALL-E 3 fixed dimensions, and leverage SDXL and Flux training buckets to prevent multi-head artifacts.
Recommended AI Image Generators Resolutions & Ratios
The table below provides exact pixel dimensions, aspect ratios, and format requirements for all current AI Image Generators visual placements.
| Placement / Format | Aspect Ratio | Recommended Size | Allowed Range | Production Notes |
|---|---|---|---|---|
| Midjourney Default Square | 1:1 | 1024 × 1024 | Base generation size | Default canvas ratio when no --ar parameter is specified in prompt. |
| Midjourney Cinematic Landscape | 16:9 | 1456 × 816 (v6/v6.1) | Upscaled: up to 2912 × 1632 | Triggered with prompt parameter --ar 16:9. Optimal for desktop wallpapers and video concept art. |
| Midjourney Mobile Portrait | 9:16 | 816 × 1456 (v6/v6.1) | Upscaled: up to 1632 × 2912 | Triggered with --ar 9:16. Tailored for vertical mobile wallpapers, Stories, and character art. |
| Midjourney Classic Photo Portrait | 2:3 or 3:2 | 896 × 1344 / 1344 × 896 | Triggered with --ar 2:3 or --ar 3:2 | Matches 35mm DSLR photography. Exceptional composition balance for human portraits. |
| DALL-E 3 Standard Square | 1:1 | 1024 × 1024 | Standard default output | Square generation mode inside ChatGPT Plus and OpenAI API. |
| DALL-E 3 Widescreen | 7:4 (1.75:1) | 1792 × 1024 | Exact fixed API resolution | Landscape mode for editorial illustrations, book banners, and web heroes. |
| DALL-E 3 Vertical Portrait | 4:7 (0.57:1) | 1024 × 1792 | Exact fixed API resolution | Portrait mode for full-body character concepts and mobile backgrounds. |
| Stable Diffusion SDXL Native Buckets | Multiple (1:1, 9:7, 7:4, 12:5) | 1024×1024, 1152×896, 1344×768 | Multi-aspect training buckets | Trained on 1024x1024 total pixel equivalent buckets to avoid multi-head duplication. |
| Flux.1 Diffusion Standard | 1:1, 16:9, 9:16, 3:2 | 1024×1024, 1280×720, 720×1280 | Flexible aspect conditioning | Modern rectified-flow model with strong adherence to custom dimensions. |
Practical Production Tips for AI Image Generators
Stick to Trained Pixel Buckets to Prevent Duplication
Modern generative models like SDXL and Flux are trained on latent "buckets" holding approximately 1,048,576 total pixels (e.g. 1024×1024, 1152×896, 1344×768). Generating at non-standard extreme resolutions without proper conditioning causes duplicated limbs and multiple heads.
How to Set Aspect Ratios in Midjourney
Append --ar <width>:<height> to the end of any Midjourney prompt. For example, --ar 16:9 for widescreen, --ar 9:16 for vertical stories, or --ar 21:9 for cinematic ultrawide. Midjourney accepts any whole number ratio.
DALL-E 3 Enforces Fixed Dimensions
Unlike Midjourney, DALL-E 3 accepts only three predefined dimension pairs: 1024×1024 (square), 1792×1024 (landscape 7:4), and 1024×1792 (portrait 4:7). Prompts requesting custom aspect ratios will be mapped to the closest of these three.
Use Inpainting & Outpainting for Custom Ratios
If you need a specific target ratio (e.g. 21:9 or 4:5) from DALL-E 3, generate in the closest native mode (1792×1024) and expand the canvas using outpainting/generative fill to avoid distortion.
Need to Resize or Calculate Missing Dimensions?
Use our free Euclidean calculator to resize your graphics or compute missing heights while preserving exact platform aspect ratios.
Frequently Asked Questions
How do I change the aspect ratio in Midjourney?
To change the aspect ratio in Midjourney, add the `--ar` parameter followed by the width-to-height ratio at the very end of your prompt. For example: `/imagine prompt: cyberpunk city sunset --ar 16:9`.
What are the available image sizes in DALL-E 3?
DALL-E 3 generates images in three exact resolutions: 1024×1024 pixels (1:1 square), 1792×1024 pixels (landscape 7:4), and 1024×1792 pixels (portrait 4:7). Intermediate ratios are not natively supported by the OpenAI API.
Why do AI image generators produce duplicate bodies at wide ratios?
Diffusion models generate noise across a spatial grid. If you request an extreme aspect ratio without sufficient training data at that dimension, the model attempts to generate multiple focal subjects to fill the extra canvas, resulting in duplicate bodies or multiple heads.
What aspect ratio is best for AI character art?
The 2:3 (896×1344 in Midjourney) or 4:5 aspect ratio is considered ideal for AI character portraits. It mirrors traditional 35mm portrait photography and gives enough vertical headroom for hair and upper-body poses without stretching.