Looking for the best Gemini custom instructions for Google Sheets? This guide gives you practical prompts you can copy, plus the current setup rules in AI for Sheets.
Quick answer
Custom Instructions work best when they are short, specific, and testable. Start with output format + tone + length constraints, then add sheet context only when needed.
- Use Global Instruction for account-wide defaults (tone, language, output style).
- Use Sheet Instruction for file-specific context (column meanings, business rules).
- Avoid vague goals like “be better” — define exact response format instead.
Global vs sheet-level custom instruction
In AI for Sheets, these two instructions are combined when requests are processed:
- Global Instruction: applies to your account across spreadsheets.
- Sheet Instruction: applies only to the current Google Sheets file.
Practical pattern: keep reusable writing rules in Global, and keep dataset assumptions in Sheet-level.
Best Gemini custom instruction examples
Copy, tweak, and test these with your own sheet:
1) Language consistency
Reply in Traditional Chinese (Hong Kong). Keep technical terms in English when needed.2) Tone and audience
Write in a concise analyst tone for non-technical business users.3) Length control
Reply in 3 bullet points maximum. Each bullet under 20 words.4) Strict JSON output
Return valid JSON only with keys: summary, risk, nextAction.5) Table-ready output
Return one line only, comma-separated, no markdown, no explanation.6) SEO workflow support
For keyword tasks, output: primary keyword, secondary keywords, intent, and one CTR-focused title.How to set custom instructions in AI for Sheets
- In Google Sheets, open Extensions → AI for Sheets.
- Open ⚙️ Custom Instruction.
- Enter your Global Instruction and optional Sheet Instruction.
- Click Save, then test with a small prompt first.
Note: older videos or listings may mention a “creativity” control. Current text model control in the Custom Instruction panel is centered around Default 1x vs Smarter 5x behavior and instruction quality.
Limitations you should know
- Custom Instructions are currently a paid feature in AI for Sheets plans.
- For best reliability, keep instructions short and unambiguous.
- Sheet Agent flows may not always follow Custom Instructions the same way as formula/text workflows, so include key constraints in the prompt when needed.
Related guides
Frequently Asked Questions
What is the best Gemini custom instruction format for Google Sheets?
Use a compact structure: audience + output format + length + constraints. Example: ‘Reply in HK Traditional Chinese. Output one CSV line only. Max 20 words.’
Should I use Global Instruction or Sheet Instruction?
Use Global for stable personal defaults (tone/language), and Sheet Instruction for dataset-specific rules in one file.
Do custom instructions work for every AI for Sheets workflow?
They work best in text/formula workflows. For Sheet Agent tasks, repeat critical constraints directly in your prompt for safer outputs.
How do I improve quality without adding very long instructions?
Use short, testable rules and iterate. If needed, switch to Smarter mode for harder reasoning tasks, then compare outputs.