Definition
Citation share is a domain's percentage of all citations recorded across a set of AI-generated answers. If answers to your tracked prompts contain 400 citations in a period and 60 point to your site, your citation share is 15%. It measures how much of the source pool behind AI answers belongs to a given domain, whether that domain is yours, a competitor's, or a third party such as Reddit or a review site.
The unit is the citation, not the response. That is the main difference from citation rate, which counts the share of responses that cite you at least once. A response with ten sources contributes ten citations to the denominator, so citation share is sensitive to how many sources each engine lists (see citations per response). It is also different from AI share of voice, which counts brand mentions in the answer text. Citation share is about whose content is used as evidence; share of voice is about whose brand is named.
Your own domain's citation share has its own name: the self-citation rate. In Promptwatch, the Citations page lists every cited domain with its share of all citations, and your own domain always appears in that list, even at zero, so its percentage is your self-citation rate. A high self-citation rate means AI engines answer questions in your category from your pages, so updating your site updates the source. A low one means answers are assembled from reviews, comparison articles, forums and news, which you can influence but do not control.
At the scale of a whole engine, citation share is spread thin. In the June 2026 ChatGPT citation share data, the most cited domain, reddit.com, held 3.71% of all ChatGPT citations, Wikipedia 0.56%, and TechRadar 0.40%. Within a narrow prompt set, though, a few domains often hold a large share, and those are the pages to study.
To use citation share in GEO work:
- Filter by AI engine first. Engines favor different source types, so a blended share hides where you win and lose.
- Split by prompt type. Branded prompts cite the brand's own site heavily, while category prompts mostly cite third parties.
- Read your share next to total citation volume. A rising share with flat volume means your pages are displacing others; a falling share with rising volume can simply mean more third-party coverage.
- List the competitor and third-party domains with the highest share for your prompts, then decide whether to earn coverage on them or publish a better source.
Citation share moves when engines re-rank sources, when fresher pages appear, and when platforms change how many sources they cite, so track it over time rather than as a one-off audit. Pair it with mention rate to see whether being used as a source also gets your brand recommended.
Examples of Citation Share
- A home services brand sees its domain hold 4% of citations across 150 tracked prompts, while a single review site holds 18%, and starts by correcting its listing on that site.
- A B2B software company's self-citation rate rises from 6% to 11% in a quarter while total citations stay flat, showing its new comparison pages are replacing third-party sources.
- A team filters citation share by engine and finds its domain at 9% on Perplexity but under 1% on Google AI Overviews, where video and forum pages take a larger part of the citations.
- An agency uses monthly ChatGPT citation share reports to show a client that Reddit's share of citations in its category fell after a platform change.
