ACI™ (AI Comprehension Index) is a proprietary metric suite developed by Vibethesia that measures how well AI language models comprehend, trust, and are likely to cite a business. It consists of three sub-metrics: ACI™ (overall AI comprehension), ACI-C™ (AI Citation Confidence), and ACI-T™ (AI Topic Authority).

ACI-C™ (AI Citation Confidence) is the confidence score AI engines assign when deciding whether to cite your brand in a response. High citation confidence means AI systems consistently include you in relevant answers. Low citation confidence means you’re frequently skipped even when your content is relevant.

ACI-T™ (AI Topic Authority) measures your topical authority from an AI system perspective. It differs from traditional domain authority — AI topic authority is determined by semantic depth, content comprehensiveness, and consistent expert treatment of your core subject matter, not just by backlink counts.

How does ACI™ differ from AIFSO-7™?

AIFSO-7™ measures how well you’re optimized for AI systems — the inputs. ACI™ measures how deeply AI systems actually comprehend your brand — the output. AIFSO-7™ and ASEO+™ are the levers you control. ACI™ is what those levers produce. A business can be technically optimized (high AIFSO-7™) but still have low AI comprehension due to poor content quality or inconsistent messaging.

What is a good ACI™ score?

ACI™ scores use the same tier classification as AIFSO-7™: Needs Improvement (0–19), Lagging (20–39), Competitive (40–59), Leading (60–79), Dominant (80–100). An ACI-C™ score above 65 indicates meaningful citation probability. An ACI-T™ score above 70 means strong AI topic authority. Most businesses score in the Competitive tier (40–59) on initial scan.

How is ACI™ calculated?

ACI™ is derived from multi-model AI analysis of your website — AIFSO Scout queries multiple AI systems with prompts about your business and measures how accurately, confidently, and completely they respond. ACI-C™ analyzes citation patterns. ACI-T™ measures topical depth and semantic authority signals. ACI™ overall is a composite of these analyses.

Is ACI™ available in other AI visibility tools?

No. ACI™, ACI-C™, and ACI-T™ are proprietary metrics developed exclusively by Vibethesia and available only through AIFSO Scout. While other tools measure whether a business appears in AI answers, ACI™ measures the depth and confidence of AI comprehension — a distinction no other tool currently captures.

ACI™ — AI Comprehension Index

ACI™, ACI-C™ (Citation Confidence), and ACI-T™ (Topic Authority) summarize how deeply AI systems comprehend, trust, and cite your business.