Midjourney Prompt Guide

Basic prompt structure

A reliable Midjourney prompt structure is: subject → description/action → environment → lighting → style/medium → parameters. For example: “a lone lighthouse keeper climbing spiral stairs, storm outside, warm lantern light, oil painting, --ar 3:2”. Put your most important details first — Midjourney's natural language processing gives progressively less weight to words after roughly the 60-word mark.

Using the --ar parameter correctly

Add --ar followed by a whole-number width:height ratio to the end of your prompt to control the output shape, for example --ar 16:9 for widescreen or --ar 9:16 for a phone wallpaper. Midjourney defaults to 1:1 (square) if you omit it. Rather than guessing or doing the math yourself, generate the exact parameter with the Midjourney Aspect Ratio Calculator.

Common mistakes that waste generations

The most common mistake is over-specifying: piling on ten adjectives dilutes focus rather than sharpening it. The second is contradiction — asking for both “minimalist” and “highly detailed” in the same prompt confuses the model's interpretation. The third is describing dimensions in prose (“wide landscape shot”) instead of using --ar, which is both more precise and doesn't eat into your effective word budget.

Checking your prompt length before you generate

Midjourney enforces a hard 6,000 character limit, and prompts over that length are rejected outright. Long before you hit that wall though, you'll hit the practical ~60-word sweet spot where additional words stop meaningfully changing the result. Check both numbers at once with the Midjourney Character Counter before you run /imagine.