- Syntax
- --ar <width>:<height>
- Values
- Whole-number ratios, e.g. 1:1, 3:2, 2:3, 16:9, 9:16
- Default
- 1:1
What it does
The --ar parameter controls the shape of the canvas Midjourney generates on, expressed as width:height. Without it, images are square (1:1). Set it to match where the image will be used — 16:9 for widescreen, 2:3 for a portrait print, 9:16 for a phone screen.
Aspect ratio is applied at generation time, so it shapes composition from the start rather than being a crop afterwards. Very extreme ratios can push the model to repeat or stretch subjects, so stay near common ratios unless you specifically want a panorama.
Examples
a mountain landscape --ar 16:9Widescreen, cinematic framing.
portrait of a knight --ar 2:3Vertical, poster-style proportions.
Common mistakes
- Using non-whole numbers — ratios must be whole numbers (2:3, not 2.5:3).
- Placing --ar in the middle of the prompt; parameters go at the very end.
- Very extreme ratios (e.g. 1:5) that cause repeated or distorted subjects.
When the parameters behind a result — aspect ratio included — travel with the image in a searchable catalog, reproducing a look at a new size is a parameter tweak, not a guessing game.
Frequently asked questions
Frequently Asked Questions
Quick answers to the most common questions.
Related parameters
Keep the parameters behind every Midjourney image
Numonic pulls your Midjourney exports into a searchable catalog with the prompt, parameters, and Job ID intact — so the exact settings behind a look you loved are one search away, not lost in a folder.