Model comparison
Grok 4 Fast (Reasoning) vs o3-pro
Head-to-head evidence from 2 shared benchmark results across 1 category. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Grok 4 Fast (Reasoning) #76 (Supported); o3-pro #127 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Grok 4 Fast (Reasoning) and o3-pro share 2 comparable benchmark results. 0 of 8 categories are comparable. 11 results are unique to Grok 4 Fast (Reasoning); 0 to o3-pro.
Updated July 23, 2026- Shared results
- 2
- Grok 4 Fast (Reasoning) only
- 11
- o3-pro only
- 0
- Comparable categories
- 0 / 8
Benchmark data for Grok 4 Fast (Reasoning) and o3-pro is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 2 shared benchmark results across 1 evidence category; 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 200K for o3-pro.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Grok 4 Fast (Reasoning) | o3-pro | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Grok 4 Fast (Reasoning)Not available | o3-pro$20 input / $80 output | A complete price comparison is not available. |
| Generation speedtokens per second | Grok 4 Fast (Reasoning)Not available | o3-pro27 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Grok 4 Fast (Reasoning)Not available | o3-pro84.93 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Grok 4 Fast (Reasoning)2M | o3-pro200K | Grok 4 Fast (Reasoning) lists the larger context window. |
Benchmark Deep Dive
Agentic1 benchmarks
| Benchmark | Grok 4 Fast (Reasoning) | o3-pro | Result |
|---|---|---|---|
| τ²-bench resultsSource | 65.8% | — | Not comparable |
Coding2 benchmarks
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | Grok 4 Fast (Reasoning) | o3-pro | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 27.4% | 32.5% | o3-pro leads |
| AA-GPQA DiamondSource | 84.7% | 84.5% | Grok 4 Fast (Reasoning) leads |
| AA-HLESource | 17.0% | — | Not comparable |
| AA-Omniscience IndexSource | -28.4% | — | Not comparable |
| AA-Omniscience AccuracySource | 22.6% | — | Not comparable |
| AA-Omniscience Hallucination RateSource | 66.0% | — | Not comparable |
Multimodal1 benchmarks
| Benchmark | Grok 4 Fast (Reasoning) | o3-pro | Result |
|---|---|---|---|
| AA-MMMU-ProSource | 61.8% | — | Not comparable |
Inst. Following1 benchmarks
| Benchmark | Grok 4 Fast (Reasoning) | o3-pro | Result |
|---|---|---|---|
| AA-IFBenchSource | 50.5% | — | Not comparable |
Frequently Asked Questions (3)
Can I compare Grok 4 Fast (Reasoning) and o3-pro 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 Grok 4 Fast (Reasoning) and o3-pro today?
o3-pro: $20.00 input / $80.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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