Claude Sonnet 4.5 vs Grok 4
Claude Sonnet 4.5 (2025) and Grok 4 (2025) are frontier-tier reasoning models from Anthropic and xAI. Claude Sonnet 4.5 ships a 200K-token context window, while Grok 4 ships a 256k-token context window. On MMLU PRO, Grok 4 leads by 1 pts. On pricing, Grok 4 costs $1.25/1M input tokens versus $3/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Grok 4 is ~140% cheaper at $1.25/1M; pay for Claude Sonnet 4.5 only for vision-heavy evaluation.
Decision scorecard
Local evidence first| Signal | Claude Sonnet 4.5 | Grok 4 |
|---|---|---|
| Decision fit | RAG, Agents, and Long context | Coding, RAG, and Agents |
| Context window | 200K | 256k |
| Cheapest output | $15/1M tokens | $2.5/1M tokens |
| Provider routes | 7 tracked | 4 tracked |
| Shared benchmarks | 1 rows | MMLU PRO leader |
Decision tradeoffs
- Claude Sonnet 4.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Claude Sonnet 4.5 for RAG, Agents, and Long context.
- Grok 4 leads the largest shared benchmark signal on MMLU PRO by 1 points.
- Grok 4 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Grok 4 has the lower cheapest tracked output price at $2.5/1M tokens.
- Grok 4 uniquely exposes Code execution in local model data.
- Local decision data tags Grok 4 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
Claude Sonnet 4.5
$6,150
Cheapest tracked route: Microsoft Foundry
Grok 4
$1,625
Cheapest tracked route: xAI Console
Estimated monthly gap: $4,525. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Microsoft Foundry, OpenRouter, and Replicate API; start route-level A/B tests there.
- Grok 4 is $12.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Grok 4 adds Code execution in local capability data.
- Provider overlap exists on Microsoft Foundry, Replicate API, and OpenRouter; start route-level A/B tests there.
- Claude Sonnet 4.5 is $12.50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Code execution before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-09-29 | 2025-07-09 |
| Context window | 200K | 256k |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-12 | - |
Pricing and availability
| Pricing attribute | Claude Sonnet 4.5 | Grok 4 |
|---|---|---|
| Input price | $3/1M tokens | $1.25/1M tokens |
| Output price | $15/1M tokens | $2.5/1M tokens |
| Providers |
Capabilities
| Capability | Claude Sonnet 4.5 | Grok 4 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
Benchmarks
| Benchmark | Claude Sonnet 4.5 | Grok 4 |
|---|---|---|
| MMLU PRO | 86.0 | 87.0 |
Deep dive
On shared benchmark coverage, MMLU PRO has Claude Sonnet 4.5 at 86 and Grok 4 at 87, with Grok 4 ahead by 1 points. The largest visible gap is 1 points on MMLU PRO, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on code execution: Grok 4. Both models share vision, multimodal input, reasoning mode, and function calling, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Claude Sonnet 4.5 lists $3/1M input and $15/1M output tokens, while Grok 4 lists $1.25/1M input and $2.5/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Grok 4 lower by about $4.97 per million blended tokens. Availability is 7 providers versus 4, so concentration risk also matters.
Choose Claude Sonnet 4.5 when vision-heavy evaluation and broader provider choice are central to the workload. Choose Grok 4 when coding workflow support, larger context windows, and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Sonnet 4.5 or Grok 4?
Grok 4 supports 256k tokens, while Claude Sonnet 4.5 supports 200K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Sonnet 4.5 or Grok 4?
Grok 4 is cheaper on tracked token pricing. Claude Sonnet 4.5 costs $3/1M input and $15/1M output tokens. Grok 4 costs $1.25/1M input and $2.5/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Sonnet 4.5 or Grok 4 open source?
Claude Sonnet 4.5 is listed under Proprietary. Grok 4 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Sonnet 4.5 or Grok 4?
Both Claude Sonnet 4.5 and Grok 4 expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Claude Sonnet 4.5 or Grok 4?
Both Claude Sonnet 4.5 and Grok 4 expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Claude Sonnet 4.5 and Grok 4?
Claude Sonnet 4.5 is available on Microsoft Foundry, Anthropic, Snowflake Cortex, GCP Vertex AI, and AWS Bedrock. Grok 4 is available on Microsoft Foundry, OpenRouter, Replicate API, and xAI Console. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-16. Data sourced from public model cards and provider documentation.