Claude Opus 4.8 vs Grok 4 Heavy
Claude Opus 4.8 (2026) and Grok 4 Heavy (2025) are frontier reasoning models from Anthropic and xAI. Claude Opus 4.8 ships a 1m-token context window, while Grok 4 Heavy ships a 256k-token context window. On SWE-bench Pro, Claude Opus 4.8 leads by 29.4 pts. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
Claude Opus 4.8 is safer overall; choose Grok 4 Heavy when provider fit matters.
Decision scorecard
Local evidence first| Signal | Claude Opus 4.8 | Grok 4 Heavy |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | multimodal apps |
| Decision fit | Coding, RAG, and Agents | Coding, Long context, and Vision |
| Context window | 1m | 256k |
| Cheapest output | $25/1M tokens | - |
| Provider routes | 7 tracked | 0 tracked |
| Shared benchmarks | SWE-bench Pro leader | 1 rows |
Decision tradeoffs
- Claude Opus 4.8 leads the largest shared benchmark signal on SWE-bench Pro by 29.4 points.
- Claude Opus 4.8 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Opus 4.8 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Opus 4.8 uniquely exposes Vision, Reasoning, and Function calling in local model data.
- Local decision data tags Claude Opus 4.8 for Coding, RAG, and Agents.
- Local decision data tags Grok 4 Heavy for Coding, Long context, and Vision.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Opus 4.8
$10,250
Cheapest tracked route/tier: Anthropic
Grok 4 Heavy
Unavailable
No complete token price in local provider data
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for Claude Opus 4.8 and Grok 4 Heavy; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision, Reasoning, and Function calling before moving production traffic.
- No overlapping tracked provider route is sourced for Grok 4 Heavy and Claude Opus 4.8; plan for SDK, billing, or endpoint changes.
- Claude Opus 4.8 adds Vision, Reasoning, and Function calling in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-28 | 2025-07-09 |
| Context window | 1m | 256k |
| Parameters | — | — |
| Architecture | decoder only | - |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2026-01 | 2024-11 |
Pricing and availability
| Pricing attribute | Claude Opus 4.8 | Grok 4 Heavy |
|---|---|---|
| Input price | $5/1M tokens | - |
| Output price | $25/1M tokens | - |
| Providers | - |
Capabilities
| Capability | Claude Opus 4.8 | Grok 4 Heavy |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | Yes | No |
| Parallel agents | Yes | No |
Benchmarks
| Benchmark | Claude Opus 4.8 | Grok 4 Heavy |
|---|---|---|
| SWE-bench Pro | 69.2 | 39.8 |
Deep dive
On shared benchmark coverage, SWE-bench Pro has Claude Opus 4.8 at 69.2 and Grok 4 Heavy at 39.8, with Claude Opus 4.8 ahead by 29.4 points. The largest visible gap is 29.4 points on SWE-bench 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 vision: Claude Opus 4.8, reasoning mode: Claude Opus 4.8, function calling: Claude Opus 4.8, tool use: Claude Opus 4.8, structured outputs: Claude Opus 4.8, and code execution: Claude Opus 4.8. Both models share multimodal input, 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.
Pricing coverage is uneven: Claude Opus 4.8 has $5/1M input tokens and Grok 4 Heavy has no token price sourced yet. Provider availability is 7 tracked routes versus 0. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Claude Opus 4.8 when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose Grok 4 Heavy when provider fit 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 Opus 4.8 or Grok 4 Heavy?
Claude Opus 4.8 supports 1m tokens, while Grok 4 Heavy supports 256k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Claude Opus 4.8 or Grok 4 Heavy open source?
Claude Opus 4.8 is listed under Proprietary. Grok 4 Heavy 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 Opus 4.8 or Grok 4 Heavy?
Claude Opus 4.8 has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Claude Opus 4.8 or Grok 4 Heavy?
Both Claude Opus 4.8 and Grok 4 Heavy expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for reasoning mode, Claude Opus 4.8 or Grok 4 Heavy?
Claude Opus 4.8 has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Claude Opus 4.8 and Grok 4 Heavy?
Claude Opus 4.8 is available on Anthropic, AWS Bedrock, GCP Vertex AI, Microsoft Foundry, and OpenRouter. Grok 4 Heavy is available on the tracked providers still being sourced. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-28. Data sourced from public model cards and provider documentation.