Quick Take

SpaceXAI’s Grok 4.5 and Anthropic’s Claude Fable 5 represent two distinct approaches to the current AI landscape. Grok 4.5, released on July 8, 2026, focuses on rapid, cost-effective performance. In contrast, Claude Fable 5, released on June 9, 2026, prioritizes raw intelligence and specialized reasoning capabilities, positioning itself as a premium tool for complex problem-solving.

Benchmark Read

Claude Fable 5 leads in core intelligence metrics, boasting an Intelligence Index of 59.9 compared to Grok 4.5’s 53.8. This trend continues in coding, where Claude scores 76.5 against Grok’s 72.4.

Looking at specific benchmarks:

• GPQA: Grok 4.5 (0.931) slightly edges out Claude Fable 5 (0.926).
• SciCode: Claude Fable 5 leads with 0.602, compared to Grok’s 0.541.
• LCR: Claude Fable 5 scores 0.7, while Grok 4.5 scores 0.677.
• HLE: Claude Fable 5 shows a significant lead at 0.533 versus Grok’s 0.403.

Claude Fable 5 also demonstrates strength in specialized testing, including TAU2 (0.985) and TerminalBench Hard (0.628).

Cost and Speed

Grok 4.5 is significantly more affordable, with a blended cost of $3.00/1M tokens, compared to Claude Fable 5’s $20.00/1M. Grok also offers superior latency, with a time-to-first-token of 17.192s and an output speed of 95.563 tok/s. Claude Fable 5 is slower, with a time-to-first-token of 46.224s and an output speed of 67.862 tok/s.

Best Fit

Grok 4.5 is best suited for high-volume applications where speed and cost-efficiency are critical. Claude Fable 5 is the ideal choice for users requiring the highest possible performance on complex coding and scientific reasoning tasks, where the increased cost is justified by the depth of output.