Claude Sonnet 4.5 vs Grok-3
Claude Sonnet 4.5 (2025) and Grok-3 (2026) are frontier-tier reasoning models from Anthropic and xAI. Claude Sonnet 4.5 ships a 200K-token context window, while Grok-3 ships a 1M-token context window. On MMLU PRO, Claude Sonnet 4.5 leads by 6.1 pts. On pricing, Grok-3 costs $0.8/1M input tokens versus $3/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Grok-3 is ~275% cheaper at $0.8/1M; pay for Claude Sonnet 4.5 only for vision-heavy evaluation.
Specs
| Released | 2025-09-29 | 2026-01-15 |
| Context window | 200K | 1M |
| Parameters | — | 1B |
| Architecture | decoder only | - |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-12 | 2025-04 |
Pricing and availability
| Claude Sonnet 4.5 | Grok-3 | |
|---|---|---|
| Input price | $3/1M tokens | $0.8/1M tokens |
| Output price | $15/1M tokens | $2.4/1M tokens |
| Providers |
Capabilities
| Claude Sonnet 4.5 | Grok-3 | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
| Benchmark | Claude Sonnet 4.5 | Grok-3 |
|---|---|---|
| MMLU PRO | 86.0 | 79.9 |
| Massive Multi-discipline Multimodal Understanding | 77.8 | 78.0 |
Deep dive
On shared benchmark coverage, MMLU PRO has Claude Sonnet 4.5 at 86 and Grok-3 at 79.9, with Claude Sonnet 4.5 ahead by 6.1 points; Massive Multi-discipline Multimodal Understanding has Claude Sonnet 4.5 at 77.8 and Grok-3 at 78, with Grok-3 ahead by 0.2 points. The largest visible gap is 6.1 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 is close: both models cover vision, multimodal input, reasoning mode, function calling, and tool use. That makes context budget, benchmark fit, and provider maturity more important than a simple checklist. If your application depends on one integration detail, verify it against the provider route you plan to use, not just the base model listing.
For cost, Claude Sonnet 4.5 lists $3/1M input and $15/1M output tokens, while Grok-3 lists $0.8/1M input and $2.4/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Grok-3 lower by about $5.32 per million blended tokens. Availability is 8 providers versus 3, 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-3 when long-context analysis, 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-3?
Grok-3 supports 1M 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-3?
Grok-3 is cheaper on tracked token pricing. Claude Sonnet 4.5 costs $3/1M input and $15/1M output tokens. Grok-3 costs $0.8/1M input and $2.4/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Sonnet 4.5 or Grok-3 open source?
Claude Sonnet 4.5 is listed under Proprietary. Grok-3 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-3?
Both Claude Sonnet 4.5 and Grok-3 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-3?
Both Claude Sonnet 4.5 and Grok-3 expose multimodal input. 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.
Where can I run Claude Sonnet 4.5 and Grok-3?
Claude Sonnet 4.5 is available on Microsoft Foundry, Anthropic, Snowflake Cortex, GCP Vertex AI, and AWS Bedrock. Grok-3 is available on OpenRouter, xAI Console, and Chutes AI. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.