Does ChatGPT give the same answer to everyone?
No. ChatGPT writes each answer afresh, so two people who ask the same question, or one person who asks twice, can get different replies. Saved memories, custom instructions, your approximate location, whether it searched the web and the model your plan gets each move the answer further.
Checked against the studies and help pages it cites on October 13, 2026.
Five reasons the answer differs.
Two of these make one person's answers differ from try to try. The other three make your answer differ from someone else's. All five come from OpenAI's own pages.
Each reply is written afresh
OpenAI's developer docs call its chat models non-deterministic by default: output may differ from one request to the next. Its help center adds that a setting named temperature, when above 0, makes the model write with some randomness.[1, 2] Both pages are about the API. We found no OpenAI page that says how the ChatGPT app sets these values.
It searches on some tries, and the web moves
ChatGPT may search the web when it judges a question needs current information; without a search, the reply comes from what the model learned in training. When it does search, it rewrites your question into one or more queries of its own, and OpenAI warns that results can be incomplete or out of date.[3, 4]
Memory and custom instructions
With memory on, ChatGPT can draw on past chats, saved memories, custom instructions, files in your Library and connected apps such as Gmail, and it can use saved memories to rewrite a web search. Custom instructions apply to every chat.[3, 5, 6]
Location
ChatGPT may use an approximate location from your IP address for local results, and may pass that general location to its search providers. A VPN changes it, and with memory on, a saved location can steer the search too.[3]
The model behind the reply
OpenAI says it regularly brings new models into ChatGPT and retires older ones, that the free tier's default model can change over time, and that Plus includes broader model access than Free. Different models give different output for the same prompt.[2, 7, 8, 9]
How much the answer moves.
Two studies and our own runs put numbers on how far the answer moves when the same question is asked again.
question-and-engine pairs named the same product first in every run, when we asked the same questions again within about an hour.
chance that ChatGPT or Google's AI gives the same list of brands twice, and about 1 in 1,000 for the same order.[10]
of ChatGPT's answers to SparkToro's hospital prompt named City of Hope. It came first in 25 of them.[10]
of cited sites, on average, are shared by ChatGPT's app and its API for the same request. What a developer's script gets isn't what a person sees.[11]
Our figure comes from the answers GEOFast recorded for its two demo projects (4 runs within 66 minutes for trygeo.fast, 3 within 62 for plausible.io), on 6 engines in US English, leaving out questions about the brand itself: 737 answers. A pair counts when every run answered it and one answer named a product first. It covers all 6 engines together, not ChatGPT alone, and shows how answers vary between runs made minutes apart, not a trend. For trygeo.fast, the questions were drafted by GEOFast's onboarding, not taken from measured demand.
SparkToro and Gumshoe ran 12 prompts through ChatGPT, Claude and Google's AI with 600 volunteers, 2,961 runs in all (January 2026). Volunteers kept their usual accounts and settings, so the study doesn't separate chance from personalization. It isn't peer-reviewed, and Gumshoe sells AI tracking.[10] The audit (September 2026, on arXiv) compared answers to product requests from ChatGPT, Gemini and Google's AI Overviews.[11]
What stays the same.
The wording, the order and the sources move. Whether a well-known brand is in the answer at all moves much less.
Being named moves less than the order
City of Hope was in 69 of 71 of ChatGPT's answers to one prompt and first in only 25. A brand can be a steady presence and still rarely lead the list.[10]
A known brand keeps showing up
In the runs we recorded for plausible.io on October 6 and 7, 2026, answers to questions that don't mention the brand named Plausible in 283 of 374. That is one project over two days, not a rule.
An unknown one doesn't appear by luck
In the same days' runs for our own site, 0 of 672 usable answers named GEOFast at trygeo.fast. The site was closed to search engines at the time, so that shows it couldn't be found, not that its pages lost.
So read a rate, not a reply
One answer is a draw from a spread. The share of answers that name you, counted over many tries, is the number that holds still enough to act on. Our methodology shows how we count it and how wide the range around it is.
How to see what other people get.
You can't see another person's ChatGPT. You can take your own history out of the answer and ask often enough to see the spread.
Use a temporary chat, unpersonalized
Before a temporary chat starts, you choose whether it uses your existing memories and custom instructions. Pick Unpersonalized. A temporary chat creates no new memories either way.[5]
Name the place in the question
For anything local, put the city or postal code in the question, which is OpenAI's own advice when local results show the wrong area.[3] Then the answer reflects your buyer's town, not yours.
Ask several times, in new chats
Start a new chat for each try and count the answers that name you. The ChatGPT guide has the five steps and how many tries make a number worth trusting.
A free first look
GEOFast's free X-ray checks how AI crawlers read your site. It then asks ChatGPT, Perplexity and Gemini three buyer questions once each, and with a free account six once each: 18 answers, a first look and not a measurement.
Counted for you
AI visibility tracking asks the same questions on a schedule, the same way each time, and shows each rate with its 90% range.
Questions about ChatGPT's answers.
Why does ChatGPT give different answers to the same question?
It writes each reply afresh, and OpenAI describes its chat models as non-deterministic by default. On top of that, one try may search the web and the next may not, and the search itself can return other pages.
Does ChatGPT give different answers to different people?
Yes. With memory on, ChatGPT can draw on a person's past chats, saved memories and custom instructions. It may use their approximate location for local results, and the model behind the reply depends on their plan and on when they ask.
Can I make ChatGPT give the same answer every time?
Not fully. OpenAI's API lets developers fix a seed and keep every setting the same to get mostly the same output, and says results can still change when it updates its systems. In the app, a temporary chat set to Unpersonalized leaves out your memories and custom instructions. It doesn't promise the same reply twice.
Does ChatGPT use my location?
It may use an approximate location from your IP address to give local results, and a VPN changes that. Sharing your device's precise location is optional and off by default.
If answers change, how do I know whether ChatGPT recommends my business?
Ask the questions your buyers ask, several times each, in new temporary chats, and count the answers that name you. One reply tells you little. A share of many replies tells you where you stand. How to check if ChatGPT mentions your brand
Where each fact comes from.
Each numbered source is the page a fact comes from: published studies and the AI companies' own help pages, read on October 13, 2026. The answers above repeat facts marked in the guide. Help pages change, so check them before you act.
- 1OpenAI: Advanced usage: Reproducible outputsdevelopers.openai.com/api/docs/guides/advanced-usage
- 2OpenAI: Why am I getting different completions on Playground vs. the API?help.openai.com/en/articles/6643200-why-am-i-getting-different-completions-on-playground-vs-the-api
- 3OpenAI: Searching the web with ChatGPThelp.openai.com/en/articles/9237897-searching-the-web-with-chatgpt
- 4OpenAI: Does ChatGPT tell the truth?help.openai.com/en/articles/8313428-does-chatgpt-tell-the-truth
- 5OpenAI: Memory in ChatGPThelp.openai.com/en/articles/8590148-memory-in-chatgpt
- 6OpenAI: ChatGPT Custom Instructionshelp.openai.com/en/articles/8096356-chatgpt-custom-instructions
- 7OpenAI: What to expect when models changehelp.openai.com/en/articles/20001053-what-to-expect-when-models-change
- 8OpenAI: ChatGPT Free Tier FAQhelp.openai.com/en/articles/9275245-chatgpt-free-tier-faq
- 9OpenAI: What is ChatGPT Plus?help.openai.com/en/articles/6950777-what-is-chatgpt-plus
- 10SparkToro: NEW Research: AIs are highly inconsistent when recommending brands or products; marketers should take care when tracking AI visibilitysparktoro.com/blog/new-research-ais-are-highly-inconsistent-when-recommending-brands-or-products-marketers-should-take-care-when-tracking-ai-visibility/
- 11Uberti-Bona Marin et al., arXiv: “If I Had to Buy Just ONE: Galaxy S26 Ultra”: Auditing AI-Generated Product Recommendationsarxiv.org/abs/2609.18729
Keep reading
- The free AI visibility checkerCheck your AI visibility for free: what AI crawlers can read on your site, then who ChatGPT, Perplexity and Gemini name for three of your buyers' questions.
- The free AI visibility change checkerIs your AI visibility change real or noise? Enter two mention counts and get each rate's 90% range and a verdict, by the rule GEOFast's dashboard uses.
- AI visibility tracking across six AI enginesTrack how often ChatGPT, AI Overviews, AI Mode, Gemini, Perplexity and Claude name you, put you first and cite your site, with a 90% range on every rate.
- AI visibility tools, comparedEvery tool we have checked, by starting price.
- What is GEOGEO, generative engine optimization, in plain words: how AI answers pick their sources, what research shows helps, and how to measure your AI visibility.
- AEO vs GEO vs SEOAEO vs GEO vs SEO: where each name came from, what Google and Microsoft say, the work all three share, and the four things that change with AI answers.
- Check if ChatGPT mentions your brandCheck by hand in five steps, see why one chat can't measure it (answers change, memory, location, leading questions), and where ChatGPT and Claude do help.
- Find the competitors ChatGPT recommendsA method for finding who ChatGPT recommends instead of you: which questions to ask, how many times, how to count the names and work out your share of voice.
- AI visibility metricsMention rate, first-pick rate, citation rate, share of voice and sentiment: what each one counts, how to work it out, and why each needs a range.
- Get ChatGPT to recommend your businessWhat gets a business named in ChatGPT's answers: what you control, whether you can submit your business, how long changes take, and how to measure it honestly.
- Get cited by ChatGPTHow ChatGPT search finds and picks the pages it links, from OpenAI's docs, what makes a page usable as a source, and which kinds of pages our data shows cited.
- Why ChatGPT doesn't show your websiteSix reasons ChatGPT leaves a site out, in the order to check them: robots.txt, firewalls, noindex, JavaScript, Bing's index and who the pages it reads name.
- Does ChatGPT use Google or Bing?What OpenAI documents about where ChatGPT search gets results (Bing, its own crawler and index), what is only reported about Google, and what it means for you.
- Rank in Google's AI OverviewsWhat Google says you need to show up in AI Overviews, how query fan-out and nosnippet work, and what studies show: 38% of cited pages rank in the top 10.
- Rank in Google AI ModeWhat sets Google's AI Mode apart from AI Overviews: query fan-out, follow-ups, a custom Gemini and Search Console's counts, and how often the two cite one page.
- Perplexity SEOHow Perplexity finds, reads and cites pages: its two crawlers, what its docs say and leave out, the Cloudflare dispute, studies, and what our runs show.
- Which AI crawlers to allowWhich AI crawlers feed ChatGPT, Claude, Perplexity and Google's answers, which only train models, and what the 1,529 of 1,605 cited sites we could read allow.
- robots.txt for AI crawlersCopy-ready robots.txt rules that keep AI search crawlers in and training crawlers out, how each crawler reads the file, and the mistakes that lock AI out.
- What is llms.txt?llms.txt is a Markdown file that tells AI agents what a site holds. Its format, a real example, who reads it today, and what studies show about its effect.
- Firewalls that block AI crawlersCloudflare, Vercel, AWS WAF and others can turn AI crawlers away even when robots.txt lets them in. Where each setting lives and how to let crawlers through.
- Do AI crawlers render JavaScript?Google's and Bing's crawlers render JavaScript. OpenAI, Anthropic and Perplexity don't say, and Vercel's 2024 study found theirs don't. Our data on cited pages.
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