Output formatting

Format is part of the request

The same information can be a wall of text, a tidy table or a block of data your spreadsheet can import. If you don't say which you want, the AI picks — and it often picks long paragraphs or an elaborate layout with headings you didn't need. Specifying the format is one of the fastest ways to make output immediately useful.

Think about where the output is going: an email, a slide, a chat message, a spreadsheet, a program. Then ask for the format that fits that destination.

Lists

Lists work well for steps, options and quick scanning. Be specific about the type and number.

Tables

Tables are ideal for comparisons. Name the columns you want, in order.

Compare these three budget laptops for a university student: [Laptop A], [Laptop B], [Laptop C].

Return a markdown table with columns: Model | Price range | Battery life | Weight | Best for.
After the table, add one sentence recommending one for a student who mostly writes essays and takes notes.
If you're unsure of a spec, write "check" rather than guessing.

JSON and other structured data

When output will be read by code or pasted into a tool, ask for JSON (or CSV) and describe the exact shape. Showing a template is the most reliable way.

Extract the event details from the message below. Return only valid JSON, with no extra text before or after, in exactly this shape:

{
  "title": string,
  "date": "YYYY-MM-DD" or null,
  "location": string or null,
  "attendees": [string]
}

Use null for anything not mentioned.

Message: "Team lunch at Rosa's on the 14th of March 2025 — me, Jen, Omar and Li."

Notice a subtle issue: "me" was dropped from attendees because the AI didn't know who "me" was. Formatting instructions make output predictable, but you still need to check it — and, for code, validate it. Many AI platforms also offer a "structured output" or "JSON mode" setting that enforces valid JSON; use it when it's available.

Markdown, headings and plain text

Many chat tools render markdown (bold, headings, bullet points). That's great in the chat window but messy if you paste into an email client or a plain-text field. Say what you need:

• "Use markdown headings and bullet points" for documents and notes.
• "Plain text only — no markdown symbols, no bullet characters" for emails, text messages or forms.

Controlling length

Length is a format choice too. Vague words like "short" or "detailed" mean different things to different people. Use concrete measures:

• Counts: "3 bullet points," "one paragraph," "two options."
• Approximate word limits: "about 100 words," "under 50 words."
• Purpose-based: "short enough to fit on one slide," "a tweet-length summary."

Combining format instructions

You can stack several format requirements, but keep them organised. A short "Format:" section at the end of a prompt is easy for both you and the AI to follow:

Summarise the meeting notes below for people who missed the meeting.

Format:
- A one-sentence headline
- "Decisions" — bullet list
- "Action items" — table with columns Owner | Task | Due date
- Under 200 words total, plain markdown

Notes:
"""
[paste notes]
"""