Prompt Coverage

Prompt coverage is the percentage of a tracked prompt set in which your brand appears in answers from generative engines. If you track 50 prompts and show up in 15, your prompt coverage is 30%. Instead of one keyword ranking, it measures how broadly you appear across the many questions buyers actually ask.

Why It Matters

In AI search, people phrase the same intent dozens of different ways. Where traditional SEO judged visibility by a single keyword rank, AI visibility is a question of frequency and breadth — how many different prompts return your brand in the answer. Low coverage means your brand is simply absent from large parts of the buyer journey, leaving those answers to competitors. Because coverage shows not just a score but which prompts include you and which don't, it pinpoints the exact gaps your content strategy needs to close.

How It's Measured

Fix a representative set of prompts tied to your brand and category, then check — repeatedly, per engine (ChatGPT, Gemini, Perplexity) — whether your brand appears in each prompt's answer, and divide appearances by the total prompt set. The key discipline is keeping the prompt set fixed: expanding it mid-cycle inflates raw mentions without showing real improvement. Coverage varies by engine, so it is most accurate when tracked per engine.

How It Differs From Adjacent Metrics

• Prompt volume measures how often a prompt is asked (demand); prompt coverage measures how broadly you appear across those prompts (supply).
• Share of model measures your weight versus competitors within the answers you appear in; coverage is about how many questions you appear in at all.
• AI visibility is the umbrella concept spanning appearances, citations, and mentions; prompt coverage quantifies that visibility along the breadth-of-prompts axis.

Sources:

• AI visibility tools: How to track and grow your presence in AI search — Search Engine Land
• AEO prompt tracking for marketing teams — HubSpot
• How to measure and report on AI search visibility — Semrush