xAI announced the Grok-4-Fast model in September 2025, which integrates "reasoning" and "non-reasoning" modes into a unified architecture whilst using 40% fewer thinking tokens than the Grok-4 model. The Grok-4-Fast can process up to 2 million text units at once and has been trained to use external tools effectively. As a result, it can browse the internet, run code, and operate other digital tools.
It is available through the xAI API in two versions: grok-4-fast-reasoning and grok-4-fast-non-reasoning, both priced at $0.20/1 million input tokens (<128k) and $0.50/1 million output tokens (<128k), whilst cached input tokens are available at $0.05/1 million. Grok-4-Fast delivers outstanding performance on mathematical and scientific reasoning tasks: 92.0% on the AIME 2025 competition (secondary school mathematics problems), 93.3% on the HMMT 2025 test (Harvard–MIT mathematics tournament), 85.7% on the GPQA Diamond assessment (doctoral-level scientific questions) and 80.0% on the LiveCodeBench programming test (January–May), whilst using on average 40% fewer thinking tokens than Grok-4.
According to an independent review by Artificial Analysis, Grok-4-Fast exhibits the best price-to-intelligence ratio amongst publicly available frontier models, and xAI reports a 98% reduction in price to achieve the same performance as Grok-4. According to xAI's published model card, Grok-4-Fast was trained using large-scale reinforcement learning to maximise intelligence density, with explicit post-training on tool use and safety demonstrations. Its unified model architecture is steerable via system prompts, thereby reducing end-to-end latency and token costs, making it ideal for real-time applications such as search and interactive coding.
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Grok 4 Fast delivers cost-efficient intelligence with a 2M token context window and unified reasoning architecture.
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初めて衣装を用意する際は、必要な付属品と別途準備するものを先に整理すると進めやすくなります。サイズやセット内容を確認する場合は、ブルアカ コスプレ衣装から候補を探せます。最後に衣装全体を試着し、正面だけでなく横や後ろからもシルエットを確認すると安心です。
Grok 4 Fast is a streamlined version of xAI’s flagship model
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Asif Razzaq
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