AI knowledge cutoff dates (updated June 2026)

A knowledge cutoff is the date after which an AI model has no built-in information. The model was trained on text gathered up to that date, so it has not memorized anything published afterwards. Ask about an event from after the cutoff and the model either says it does not know, or it searches the web (if the product supports browsing) to answer.

It depends on the model behind ChatGPT. GPT-5.5 (the current default since May 2026) has a December 2025 cutoff. GPT-5.2 has August 2025, GPT-5 has September 2024, GPT-4o has October 2023, and the original GPT-4 had September 2021. ChatGPT can also browse the web, so for current questions it pulls live results regardless of the underlying cutoff.

GPT-4o has an October 2023 knowledge cutoff and was released on May 13, 2024. OpenAI began retiring GPT-4o from ChatGPT in late 2025 in favor of the GPT-5 series.

GPT-4 was released on March 14, 2023. Its original training cutoff was September 2021. The default gpt-4 alias in the API now resolves to a newer snapshot with a knowledge cutoff around December 2023.

It varies by version. Claude Opus 4.8 (released May 2026) has a January 2026 reliable knowledge cutoff. Claude 3.5 Sonnet had April 2024, and Claude 3 had August 2023. Anthropic publishes two dates per model: a later training-data cutoff and an earlier reliable knowledge cutoff (the date through which the model answers dependably). We list the reliable cutoff.

Google's recent models (Gemini 2.5 and Gemini 3 Pro) carry a January 2025 cutoff. Gemini 2.0 Flash is around August 2024. Google did not publish official cutoffs for the Gemini 1.0 and 1.5 generations. Gemini answers most live queries through Google Search grounding rather than memory alone.

DeepSeek does not officially publish knowledge cutoffs for its models. DeepSeek-V3 shipped in December 2024, R1 in January 2025, and V4 in April 2026, so each model's data ends shortly before its release, but the company has not stated exact cutoff dates.

The training data cutoff is the last date that any data was included in training. The reliable knowledge cutoff is the date through which the model answers dependably, which is usually earlier because the most recent months are thin and less reliable. Release date is different again: it is when the public could first use the model, typically several months to over a year after the cutoff.

As of June 2026, Claude Opus 4.8 and Claude Fable 5 lead with a January 2026 cutoff, followed by OpenAI GPT-5.5 and xAI Grok 4.3 (both December 2025). These dates move every few months as new models ship, which is why we review this page monthly.

Not entirely. When a model browses the web (as ChatGPT, Gemini, Perplexity, Copilot, and Grok can), it can answer questions about events after its cutoff. But browsing only fires for some queries, the model still leans on its trained knowledge for everything else, and its judgment about what to trust is shaped by what it learned before the cutoff. The cutoff still matters for how a brand is understood.

Different cutoffs are a big reason. A model trained through January 2026 knows about products, funding rounds, and rebrands that a model frozen at October 2023 has never seen. The models also differ in training data, retrieval behavior, and how confidently they answer, so the same prompt produces different results across ChatGPT, Claude, Gemini, and the rest.

A model with an earlier cutoff has no memory of it. Until that content is either picked up by the model's web-browsing step or included in a future training run, the model answers as if your content does not exist. This is exactly why newer brands and pages struggle to get mentioned by AI engines, and why tracking your visibility across engines matters.

Three levers. First, publish content that the browsing-enabled models can fetch live (clean pages, an llms.txt, fast load). Second, build the third-party signals (reviews, mentions, structured data) that models trust. Third, monitor which engines actually mention you, since each has a different cutoff and retrieval behavior. FixAEO's free AI visibility checker shows where you stand across eight engines.

Every few months. The major labs ship a new flagship model two to four times a year, and each one usually advances the cutoff. Because this is a fast-moving, current-facts topic, we review and update this page monthly.