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Midjourney Aspect Ratio Calculator

Pick what you are making or type a size in pixels, inches or cm. You get the exact --ar value to paste into Midjourney, plus the pixels you need for the final file.

Results

Add this to your prompt

--ar 4:5
Shape
portrait
Width ÷ height
0.800
Final file size to export
1080 × 1350 px. Upscale or resize your Midjourney image to this size after you generate.
4:5
Shape preview

How to use the calculator

  1. Pick a preset, or choose Custom size and type your own width and height.
  2. Copy the --ar value and paste it at the end of your Midjourney prompt.
  3. Generate, then upscale or resize the image to the pixel size shown under the result.

Questions about Midjourney aspect ratios

How do I change the aspect ratio in Midjourney?

Add --ar followed by width:height to the end of your prompt, for example --ar 16:9. You can also write --aspect. On the Midjourney website you can set a default aspect ratio in the settings panel of the Imagine bar.

Can I use decimals in --ar?

No. Midjourney only accepts whole numbers. Turn decimals into whole numbers first: 8.5 x 11 inches becomes 85:110, which Midjourney simplifies to 17:22. This calculator does that step for you.

What pixel size will my Midjourney image be?

Aspect ratio sets the shape, not the exact size. The final pixel size depends on the Midjourney version and the upscaler you use. Use the ratio to get the right shape, then upscale or resize to the pixel size you need.

What aspect ratio should I use for Instagram?

Use 4:5 for a portrait feed post, 1:1 for a square post, and 9:16 for Stories and Reels. Portrait 4:5 takes up the most space in the feed.

What aspect ratio is an 8 x 10 print?

An 8 x 10 inch print is 4:5. To print it sharply at 300 DPI you need an image of 2400 x 3000 pixels, so plan to upscale.

Can I change the aspect ratio after I generate an image?

Yes. Midjourney’s pan and zoom out tools, and the Editor on the Midjourney website, can extend an image to a new shape. Setting the right --ar before you generate usually gives a cleaner composition.