Model comparison
Claude Opus 4.8 vs Grok 4 Fast (Reasoning)
Head-to-head evidence from 12 shared benchmark results across 5 categories. Overall scores shown here use BenchLM's provisional ranking lane.
Verified leaderboard positions: Claude Opus 4.8 #3; Grok 4 Fast (Reasoning) unranked
Evidence parity. Claude Opus 4.8 and Grok 4 Fast (Reasoning) share 12 comparable benchmark results. 0 of 8 categories are comparable. 41 results are unique to Claude Opus 4.8; 2 to Grok 4 Fast (Reasoning).
Updated July 12, 2026- Shared results
- 12
- Claude Opus 4.8 only
- 41
- Grok 4 Fast (Reasoning) only
- 2
- Comparable categories
- 0 / 8
Benchmark data for Claude Opus 4.8 and Grok 4 Fast (Reasoning) is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 12 shared benchmark results across 5 evidence categories; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
Grok 4 Fast (Reasoning) has the larger context window at 2M, compared with 1M for Claude Opus 4.8.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | Claude Opus 4.8 | Δ | Grok 4 Fast (Reasoning) |
|---|---|---|---|
| Agentic | Claude Opus 4.880.3 | MarginNo overlap | Grok 4 Fast (Reasoning)Not measured |
| Coding | Claude Opus 4.876.4 | MarginNo overlap | Grok 4 Fast (Reasoning)Not measured |
| Knowledge | Claude Opus 4.862.7 | MarginNo overlap | Grok 4 Fast (Reasoning)Not measured |
| Math | Claude Opus 4.853.9 | MarginNo overlap | Grok 4 Fast (Reasoning)Not measured |
| Multimodal | Claude Opus 4.877.0 | MarginNo overlap | Grok 4 Fast (Reasoning)Not measured |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude Opus 4.8 | Grok 4 Fast (Reasoning) | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude Opus 4.8$5 input / $25 output | Grok 4 Fast (Reasoning)Not available | A complete price comparison is not available. |
| Generation speedtokens per second | Claude Opus 4.8Not available | Grok 4 Fast (Reasoning)Not available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude Opus 4.8Not available | Grok 4 Fast (Reasoning)Not available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude Opus 4.81M | Grok 4 Fast (Reasoning)2M | Grok 4 Fast (Reasoning) lists the larger context window. |
Benchmark Deep Dive
Agentic19 benchmarks
| Benchmark | Claude Opus 4.8 | Grok 4 Fast (Reasoning) | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 74.6% | — | Not comparable |
| BrowseCompSource | 84.3% | — | Not comparable |
| DeepSearchQASource | 93.1% | — | Not comparable |
| OSWorld-VerifiedSource | 83.4% | — | Not comparable |
| Finance Agent v2Source | 53.9% | — | Not comparable |
| GDPval-AASource | 1600 | — | Not comparable |
| MCP AtlasSource | 82.2% | — | Not comparable |
| ToolathlonSource | 59.9% | — | Not comparable |
| Gert LabsSource | 72.97% | — | Not comparable |
| AA Agentic IndexSource | 47.2% | — | Not comparable |
| Tau2-TelecomSource | 94.4% | 65.8% | Claude Opus 4.8 leads |
| GDPval-AASource | 55.0% | — | Not comparable |
| ResearchClawBenchSource | 21.1% | — | Not comparable |
| OSWorld 2.0Source | 20.6% | — | Not comparable |
| AA BriefcaseSource | 1354 | — | Not comparable |
| AA AutomationBenchSource | 48.5% | — | Not comparable |
| AA EnterpriseOps-GymSource | 44.0% | — | Not comparable |
| AA Harvey LABSource | 7.5% | — | Not comparable |
| AA Tau3 BankingSource | 27.6% | — | Not comparable |
Coding13 benchmarks
| Benchmark | Claude Opus 4.8 | Grok 4 Fast (Reasoning) | Result |
|---|---|---|---|
| SWE-bench VerifiedSource | 88.6% | — | Not comparable |
| SWE-bench ProSource | 69.2% | — | Not comparable |
| SWE MultilingualSource | 84.4% | — | Not comparable |
| SWE MultimodalSource | 38.4% | — | Not comparable |
| Terminal-Bench 2.0Source | 74.6% | — | Not comparable |
| cursorBench31Source | 58.4% | — | Not comparable |
| cursorBench32Source | 62.3% | — | Not comparable |
| AA Coding IndexSource | 74.3% | — | Not comparable |
| Terminal-Bench HardSource | 58.3% | 18.9% | Claude Opus 4.8 leads |
| AA-SciCodeSource | 53.5% | 44.2% | Claude Opus 4.8 leads |
| FrontierCodeSource | 46.5% | — | Not comparable |
| AA Terminal-Bench 2.1Source | 84.6% | — | Not comparable |
| Vibe Code BenchSource | — | 0.00% | Not comparable |
Reasoning2 benchmarks
Knowledge10 benchmarks
| Benchmark | Claude Opus 4.8 | Grok 4 Fast (Reasoning) | Result |
|---|---|---|---|
| GPQASource | 93.6% | — | Not comparable |
| GPQA-DSource | 93.6% | — | Not comparable |
| HLESource | 57.9% | — | Not comparable |
| HLE w/o toolsSource | 49.8% | — | Not comparable |
| Artificial Analysis Intelligence IndexSource | 55.7% | 27.4% | Claude Opus 4.8 leads |
| AA-GPQA DiamondSource | 92.0% | 84.7% | Claude Opus 4.8 leads |
| AA-HLESource | 45.7% | 17.0% | Claude Opus 4.8 leads |
| AA-Omniscience IndexSource | 27.4% | -28.4% | Claude Opus 4.8 leads |
| AA-Omniscience AccuracySource | 46.6% | 22.6% | Claude Opus 4.8 leads |
| AA-Omniscience Hallucination RateSource | 35.9% | 66.0% | Claude Opus 4.8 leads |
Math3 benchmarks
Multilingual1 benchmarks
| Benchmark | Claude Opus 4.8 | Grok 4 Fast (Reasoning) | Result |
|---|---|---|---|
| INCLUDESource | 87.6% | — | Not comparable |
Multimodal6 benchmarks
Inst. Following1 benchmarks
| Benchmark | Claude Opus 4.8 | Grok 4 Fast (Reasoning) | Result |
|---|---|---|---|
| AA-IFBenchSource | 62.2% | 50.5% | Claude Opus 4.8 leads |
Frequently Asked Questions (3)
Can I compare Claude Opus 4.8 and Grok 4 Fast (Reasoning) on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for Claude Opus 4.8 and Grok 4 Fast (Reasoning) today?
Claude Opus 4.8: $5.00 input / $25.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
Related Comparisons
The AI models change fast. We track them for you.
A weekly brief for engineers and researchers covering new models, ranking shifts, and pricing changes.
Free. No spam. Unsubscribe anytime.