xAI has released Grok 4 Fast - breaking through our intelligence vs cost frontier by achieving Gemini 2.5 Pro level intelligence at a ~25X cheaper cost
Intelligence:
@xai shared with us pre-release access to Grok 4 Fast. In reasoning mode, the model scores an impressive 60 on our Artificial Analysis Intelligence Index, in line with Gemini 2.5 Pro and Claude 4.1 Opus, while sitting as expected below the prior Grok 4 release and GPT-5 (high). Grok 4 Fast performed especially well on coding evaluations, taking the number one spot on our leaderboard for LiveCodeBench, even outperforming its larger sibling Grok 4.
Cost: xAI is offering Grok 4 Fast at a very competitive price of only $0.2/1M Input Tokens and $0.5/1M output tokens. The model is also quite token efficient compared to other reasoning models, taking 61M tokens to complete our intelligence index, significantly less than Gemini 2.5 Pro’s 93M and Grok 4’s 120M. This competitive pricing and efficiency translates to the cost of running Artificial Analysis Intelligence Index being ~25X lower than Gemini 2.5 Pro and ~23X lower than GPT-5 (reasoning mode high).
Speed: When benchmarking the pre-release API, xAI’s endpoint for the model was very fast, achieving 344 output tokens per second - ~2.5X faster than OpenAI’s GPT-5 API. This also allows for End to End Latency results that are faster than most non-reasoning models for many workloads. Speeds may drop as traffic on the API increases - keep an eye on our live performance benchmarking to see how this evolves.
Congratulations to the
@xai team and
@elonmusk on this new release!
See below for more details and in-depth analysis 👇