GPT-6 Astra vs Grok 4 Fast
GPT-6 Astra leads the LLM Stats Score 60.7 to 32.0. Grok 4 Fast is 72.7x cheaper per token.
OpenAI · xAI · Updated for 2026
Which is better?
GPT-6 Astra leads the overall LLM Stats Score 60.7 to 32.0, ranking #1 overall.
In the 2 individual benchmarks reported for both models, GPT-6 Astra wins 2; this is a narrower head-to-head signal than the composite indexes.
On price, Grok 4 Fast is roughly 72.7x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Grok 4 Fast also accepts a larger context window (2,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-6 Astra
- overall performance matters — it scores 60.7 and ranks #1 on LLM Stats
- your work emphasizes reasoning and coding — it leads those capability indexes
- you value its reported benchmark strengths — it wins 2 of 2 exact shared results
- you want the most recent training data — it shipped Sep 2026
Choose Grok 4 Fast
- cost matters — it's about 72.7x cheaper per token
- you process long inputs — it offers a 2,000,000 token context window
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
22 reported for GPT-6 Astra · 7 for Grok 4 Fast
GPT-6 Astra outperforms in 2 benchmarks (BrowseComp, GPQA), while Grok 4 Fast is better at 0 benchmarks.
GPT-6 Astra significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-6 Astra ($10.00/1M tokens) is 50.0x more expensive than Grok 4 Fast ($0.20/1M tokens).
For output processing, GPT-6 Astra ($50.00/1M tokens) is 100.0x more expensive than Grok 4 Fast ($0.50/1M tokens).
In conclusion, GPT-6 Astra is more expensive than Grok 4 Fast.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Grok 4 Fast accepts 2,000,000 input tokens compared to GPT-6 Astra's 1,050,000 tokens. GPT-6 Astra can generate longer responses up to 128,000 tokens, while Grok 4 Fast is limited to 30,000 tokens.
Input capabilities
Documented input modalities across available providers
Both GPT-6 Astra and Grok 4 Fast support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-6 Astra
Grok 4 Fast
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
GPT-6 Astra was released on 2026-09-03, while Grok 4 Fast was released on 2025-08-28.
GPT-6 Astra is 12 months newer than Grok 4 Fast.
Sep 3, 2026
1 days ago
1.0yr newerAug 28, 2025
1.0 years ago
Knowledge Cutoff
When training data ends
GPT-6 Astra has a documented knowledge cutoff of 2026-04-30, while Grok 4 Fast's cutoff date is not specified.
We can confirm GPT-6 Astra's training data extends to 2026-04-30, but cannot make a direct comparison without Grok 4 Fast's cutoff date.
Apr 2026
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Provider Availability
GPT-6 Astra is available from OpenAI. Grok 4 Fast is available from xAI.
GPT-6 Astra
Grok 4 Fast
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-6 Astra and Grok 4 Fast side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-6 Astra vs Grok 4 Fast.