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How To Get The Right Length Output From AI

January 8, 20263 min read
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I asked ChatGPT for a detailed report on a company. Got 15 pages. Way too much.

I followed up asking for a concise version. Got 10 bullet points. Not enough.

Then I tried something different: "The report should take 3 minutes to read."

Perfect.


The Problem With Vague Words

Words like "concise," "detailed," "brief," and "long" mean different things to different people. And they mean different things to AI.

When you say "give me a concise summary," you're asking AI to guess. Sometimes it guesses right. Often it doesn't.

I ran an experiment. I took a simple prompt:

Give me a report on what a coding agent is.

Then I ran it through GPT-4o with different qualifiers: "Be verbose," "Be detailed," "Be concise," "Be brief," and "Make this a 2 minute read." Five runs each, same model. Look at the variance:

Vague Words

Same prompt, 5 runs each. Look at the variance.

No qualifier23% variance
246
236
297
298
268
Min: 236Avg: 269Max: 298
"Be verbose"21% variance
609
672
712
748
606
Min: 606Avg: 669Max: 748
"Be detailed"15% variance
557
633
604
551
545
Min: 545Avg: 578Max: 633
"Be concise"44% variance
66
52
55
42
56
Min: 42Avg: 54Max: 66
"Be brief"50% variance
52
44
55
57
72
Min: 44Avg: 56Max: 72

Same prompt. Same model. Different results every time.

Read Time Qualifier

Same prompt with "Make this a 2 minute read"

"2 minute read"16% variance
455
456
475
402
449
Min: 402Avg: 447Max: 475

Much tighter. The model has a clear target.

Model: GPT-4o | Prompt: "Give me a report on what a coding agent is." | See full responses

"Concise" has 87% variance. "Brief" is 25%. These vague words give wildly inconsistent results.

But "2 minute read"? Just 13% variance. The outputs cluster around 447 words, almost exactly 2 minutes at average reading speed.


Word Counts Are Meaningless

Okay, so the solution is to tell the AI exactly how long the output should be. But how many words is "a lot" or "a little"?

Quick: is 500 words a lot or a little?

How long does it take to read 300 words?

The average adult reads about 238 words per minute (based on a meta-analysis of 190 studies). Most people don't have an intuition for word counts, but everyone knows what "3 minutes" feels like.


The Fix: Use Read Time

Instead of vague qualifiers, tell AI how much of your time you want to invest in reading the output.

  • "Give me a brief summary" -> "Give me a summary I can read in 1 minute"
  • "Write a detailed report" -> "Write a report that takes 5 minutes to read"
  • "Be concise" -> "Keep this under 2 minutes to read"
  • "Make it longer" -> "Expand this to a 4 minute read"

The model knows approximately how many words fit in a "3 minute read." More importantly, you know exactly what you're asking for.


Why This Works

  • It matches your intent. You're not thinking "I want 500 words." You're thinking "I have 3 minutes to understand this."

  • It anchors the model. Instead of guessing what "brief" means to you, it has a concrete number to work toward.


What This Enables

This changes how you work with AI. You can now budget your learning time:

  • "I have 5 minutes for this brainstorming session"
  • "I want to spend 20 minutes learning about this topic today"
  • "Give me the 2 minute version now, I'll ask for more depth later"

This is something you can't do anywhere else on the internet. Blog posts are whatever length the author decided. YouTube videos are fixed. Documentation is exhaustive.

With AI, you choose exactly how much time you want to invest.


Try It

Next time you prompt AI, skip the vague words. Tell it how much of your time you're willing to spend.

Give me a 2 minute guide on how React Server Components work.

Or try this: find a blog post you've been meaning to read but haven't had time for. Paste the link and ask:

Reorganize this into a 5 minute read.

You'll get the key insights without the fluff. That's the power of controlling your own time.

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