The Lean Prompting Guide — Maximum Signal, Minimum Noise
Practical techniques for writing concise, efficient AI prompts — cut the bloat, get better results, save tokens and time.
The Lean Prompting Guide 🎯
The best prompt is the shortest one that gets the job done.
The Four Types of Prompt Fat
Before you can cut, you need to identify what to trim.
1. Preamble Fat
Unnecessary introductions and pleasantries.
| Fat | Lean |
|---|---|
| "I would like you to help me with something. I am working on a project and I need..." | "Write a project brief for..." |
| "Can you please assist me in creating..." | "Create..." |
| "I was wondering if you could help me understand..." | "Explain..." |
2. Redundancy Fat
Saying the same thing twice in different words.
| Fat | Lean |
|---|---|
| "Write a short, concise, brief summary" | "Summarise in 3 sentences" |
| "Make it professional and suitable for a business context" | "Business tone" |
| "Provide detail and be thorough and comprehensive" | "Be thorough" |
3. Hedge Fat
Qualifying everything with uncertainty.
| Fat | Lean |
|---|---|
| "If possible, could you maybe try to..." | "Do X" |
| "I think what I might need is something like..." | "I need X" |
| "It would be great if you could perhaps..." | "Do X" |
4. Instruction Fat
Over-specifying what the AI already knows.
| Fat | Lean |
|---|---|
| "Write an email. Emails should have a subject line, a greeting, a body, and a sign-off." | "Write an email about X" |
| "Create a list. Number each item. Put them in order." | "List X in order" |
| "Write a paragraph. A paragraph is typically 3-6 sentences." | "Write a paragraph about X" |
The 40-Word Rule
Challenge yourself to state every prompt in 40 words or fewer. This is not always possible — complex tasks need more context — but making it the default forces you to identify what is essential and what is padding.
Before (87 words):
"I am working on a blog post about sustainable fashion and I need help writing an introduction. The introduction should be engaging and hook the reader. It should mention the problem of fast fashion and introduce the concept of sustainable alternatives. The tone should be conversational but informative. I want it to be about 150 words long and include a surprising statistic if possible."
After (31 words):
"Write a 150-word blog intro about sustainable fashion. Conversational tone, hook the reader with a surprising statistic. Cover the fast fashion problem and introduce sustainable alternatives."
Same output quality. 64% fewer words.
When More Words Help
Not every long prompt is bloated. Legitimate reasons for longer prompts:
- Few-shot examples — showing the AI 2-3 examples of what you want
- Complex formatting requirements — tables, specific structures
- Domain-specific context — information the AI does not have
- Multi-step tasks — sequential instructions for complex workflows
- Persona specifications — detailed voice and audience requirements
The test: does removing this sentence change the output? If no, cut it.
Token Economics for API Users
For developers and power users calling AI APIs directly:
| Model | Input Cost per 1K tokens | Savings from 50% prompt reduction |
|---|---|---|
| GPT-4o | $0.005 | $0.0025 per call |
| Claude 3.5 Sonnet | $0.003 | $0.0015 per call |
| Gemini 1.5 Pro | $0.00125 | $0.000625 per call |
| At 10,000 calls/day | — | $7.50-$25/day saved |
| At 100,000 calls/day | — | $75-$250/day saved |
At enterprise scale, prompt efficiency is not a nicety — it is a cost lever.
The Lean Prompt Checklist
Before sending any prompt, run through this:
- ☐ Can I remove the first sentence? (Usually yes)
- ☐ Am I saying anything twice?
- ☐ Am I explaining something the AI already knows?
- ☐ Am I hedging or being excessively polite?
- ☐ Have I specified constraints (length, format, tone)?
- ☐ Is every word earning its place?
If you can remove a word without changing the meaning, remove it.