GPT-5.5 Pro vs Grok 4.5
GPT-5.5 Pro 
Grok 4.5 Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 61.0.
- GPT-5.5 Pro (xhigh) is stronger in maths, reasoning.
- Grok 4.5 (high) is stronger in agents & tools, coding, composite, knowledge, long context, multimodal.
- Grok 4.5 (high) is 23× cheaper ($3.00 vs $67.50 per 1M blended).
- Grok 4.5 (high) streams 13.9× faster (56 vs 4 tokens per second).
| Metric | GPT-5.5 Pro (xhigh) | Grok 4.5 (high) |
|---|---|---|
| BenchLeader Index | 67.1 | 61.0 |
| Maths score | 74.5 | 55.3 |
| Reasoning score | 80.1 | 62.3 |
| Agents & tools score | – | 50.2 |
| Coding score | – | 57.9 |
| Composite score | – | 78.6 |
| Knowledge score | – | 63.7 |
| Long context score | – | 66.1 |
| Multimodal score | – | 65.0 |
| Blended price $/M | $67.50 | $3.00 |
| Output speed | 4 tok/s | 56 tok/s |
| Time to first answer | 3.5 s | 7.7 s |
| Context window | 1.1M | 500k |
| GPQA Diamond | – | 93.4% |
| FrontierMath Tiers 1–3 | 87.7% | 57.2% |
| FrontierMath Tier 4 | 78.0% | 24.4% |
| OTIS Mock AIME | – | 97.8% |
| SimpleQA Verified | – | 48.3% |
| Terminal-Bench | – | 12.4% |
| SciCode | – | 54.0% |
| ProofBench | – | 31.0% |
| AA Intelligence Index | – | 39.1 |
| AA-LCR | – | 79.3% |
| MMMU-Pro | – | 80.4% |
| AA-Omniscience | – | 25.3 |
| GPQA Diamond (AA) | – | 93.1% |
| Humanity's Last Exam (AA) | – | 42.7% |
| SciCode (AA) | – | 55.0% |
| LiveCodeBench | – | 87.3% |
| MMLU-Pro | – | 89.2% |
| IOI | – | 40.6% |
| LegalBench | – | 86.0% |
| CorpFin | – | 67.4% |
| TaxEval | – | 71.7% |
| Terminal-Bench 2.1 (Vals) | – | 67.8% |
| SWE-bench (Vals) | – | 86.6% |
| GPQA Diamond (Vals) | – | 92.9% |
| Vals Index | – | 51.5 |
| ARC-AGI-1 | 95.0% | 85.7% |
| ARC-AGI-2 | 84.2% | 52.6% |
| ARC-AGI-3 | – | 0.3% |
| CritPt | 30.6% | 15.4% |
| GDPval (AA) | – | 46.5% |
| τ²-Bench Banking (AA) | – | 42.1% |
| Analyst Agent (AA) | – | 35.0% |
| Code Migration | – | 36.6% |
| Excel Modeling Benchmark | – | 52.9% |
| Finance Agent v2 | – | 48.4% |
| Harvey's Legal Agent Benchmark | – | 12.9% |
| Legal Research Bench | – | 38.0% |
| MedCode | – | 43.3% |
| MedScribe | – | 86.9% |
| MMMU-Pro (Vals) | – | 61.8% |
| MortgageTax | – | 61.8% |
| ProgramBench | – | 0.0% |
| SAGE | – | 35.0% |
| SkillsBench | – | 66.0% |
| SREBench | – | 0.8% |
| Terminal-Bench 4.0 (Vals) | – | 6.6% |
| Time Horizon Index: KSP | – | 6.3% |
| Vals Multimodal Index | – | 63.4% |
| Vibe Code Bench v1.1 | – | 69.0% |
| Web Search Index | – | 35.5% |
| Chess Puzzles | – | 36.0% |
| PostTrainBench | – | 23.4% |
| Surface Evolver Bench | – | 74.4% |
| DeepSWE | – | 53.8% |
| LMCA | 53.9% | 45.2% |
| DTBench | 96.0% | 96.5% |
| ALE-Bench | – | 1309.3 |
| GDP.pdf | – | 14.0% |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
GPT-5.5 Pro vs Grok 4.5: questions
- Is GPT-5.5 Pro better than Grok 4.5?
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 61.0. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 Pro (xhigh) is ahead overall as of 2026-09-19, but check the category scores for your use.
- Which is cheaper, GPT-5.5 Pro or Grok 4.5?
- Grok 4.5 is cheaper: $3.00 against $67.50 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5.5 Pro or Grok 4.5?
- Grok 4.5 streams faster: 56 against 4 output tokens per second.
- Which has the larger context window?
- GPT-5.5 Pro accepts more context: 1.1M against 500k tokens.