Claude Haiku 5.5 vs Grok-4 Fast Reasoning
Comparing Claude Haiku 5.5 and Grok-4 Fast Reasoning across benchmarks, pricing, and capabilities.
Anthropic · xAI · Updated for 2026
Which is better?
Claude Haiku 5.5 and Grok-4 Fast Reasoning trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.
On price, Claude Haiku 5.5 is roughly 1.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Grok-4 Fast Reasoning 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 Claude Haiku 5.5
- cost matters — it's about 1.4x cheaper per token
- you want the most recent training data — it shipped Oct 2026
Choose Grok-4 Fast Reasoning
- you process long inputs — it offers a 2,000,000 token context window
At a glance
The differences that matter most.
Individual benchmarks
36 reported for Claude Haiku 5.5 · 0 for Grok-4 Fast Reasoning
Claude Haiku 5.5 and Grok-4 Fast Reasoningdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Haiku 5.5 ($0.10/1M tokens) is 2.0x cheaper than Grok-4 Fast Reasoning ($0.20/1M tokens).
For output processing, Claude Haiku 5.5 ($0.50/1M tokens) costs the same as Grok-4 Fast Reasoning ($0.50/1M tokens).
In conclusion, Grok-4 Fast Reasoning is more expensive than Claude Haiku 5.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Grok-4 Fast Reasoning accepts 2,000,000 input tokens compared to Claude Haiku 5.5's 1,000,000 tokens. Claude Haiku 5.5 can generate longer responses up to 128,000 tokens, while Grok-4 Fast Reasoning is limited to 30,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Haiku 5.5 and Grok-4 Fast Reasoning support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Haiku 5.5
Grok-4 Fast Reasoning
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
Claude Haiku 5.5 was released on 2026-10-07, while Grok-4 Fast Reasoning was released on 2025-08-28.
Claude Haiku 5.5 is 14 months newer than Grok-4 Fast Reasoning.
Oct 7, 2026
1 weeks ago
1.1yr newerAug 28, 2025
1.1 years ago
Knowledge Cutoff
When training data ends
Claude Haiku 5.5 has a documented knowledge cutoff of 2026-06-01, while Grok-4 Fast Reasoning's cutoff date is not specified.
We can confirm Claude Haiku 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without Grok-4 Fast Reasoning's cutoff date.
Jun 2026
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Provider Availability
Claude Haiku 5.5 is available from Anthropic. Grok-4 Fast Reasoning is available from xAI.
Claude Haiku 5.5
Grok-4 Fast Reasoning
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Haiku 5.5 and Grok-4 Fast Reasoning side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Haiku 5.5 vs Grok-4 Fast Reasoning.