# GPT-5.5 vs Grok 4.20 > Side-by-side benchmark comparison for GPT-5.5 and Grok 4.20 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks. - Canonical page: https://benchlm.ai/compare/gpt-5-5-vs-grok-4-20-beta - Last updated: September 4, 2026 - Shared sourced benchmarks: 14 - HTML indexing: indexable - Ranking lane: BenchAlign v5 ## Quick Verdict Pick GPT-5.5 if you want the stronger benchmark profile. Grok 4.20 only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score. ## Summary - GPT-5.5 leads overall 73.27 to 67.01. - The clearest category separation is in coding, where the averages are 67.7 for GPT-5.5 and 28.2 for Grok 4.20. - The biggest single benchmark swing is Vibe Code Bench in Coding, with scores of 69.85% and 4.06%. - Grok 4.20 is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use. - Grok 4.20 also has the larger context window at 2M. ## Model Snapshot | Property | GPT-5.5 | Grok 4.20 | |----------|----------|----------| | Creator | OpenAI | xAI | | Type | Proprietary | Proprietary | | Reasoning | Reasoning | Reasoning | | Context | 1M | 2M | | Overall Score | 73.27 | 67.01 | | Benchmarks Covered | 38 | 23 | | Pricing (input/output) | $5.00 / $30.00 | $2.00 / $6.00 | ## Category Breakdown ### Agentic - Winner: GPT-5.5 - GPT-5.5 public-lane score: 63.9 (Supported · #15/151) - Grok 4.20 public-lane score: 26.5 (Supported · #144/151) | Benchmark | GPT-5.5 | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | Terminal-Bench 2.0 | 82% | 47.1% | GPT-5.5 | | CyberGym | 81.8% | Coming soon | Coming soon | | BrowseComp | 84.4% | Coming soon | Coming soon | | OSWorld-Verified | 78.7% | Coming soon | Coming soon | | MCP Atlas | 75.3% | Coming soon | Coming soon | | Toolathlon | 55.6% | Coming soon | Coming soon | | τ²-bench results | 98% | Coming soon | Coming soon | | Gert Labs | 72.93% | 38.36% | GPT-5.5 | | ResearchClawBench | 17.0% | Coming soon | Coming soon | | OSWorld 2.0 | 13.0% | Coming soon | Coming soon | | JobBench | 42.7% | Coming soon | Coming soon | | ExploitGym | 13.4% | Coming soon | Coming soon | | Terminal-Bench 2.1 (Vals) | 76.4% | 44.2% | GPT-5.5 | | DeepSearchQA | Coming soon | 62.8% | Coming soon | ### Coding - Winner: GPT-5.5 - GPT-5.5 public-lane score: 67.7 (Supported · #8/183) - Grok 4.20 public-lane score: 28.2 (Supported · #171/183) | Benchmark | GPT-5.5 | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | SWE-bench Pro | 58.6% | 51.8% | GPT-5.5 | | Terminal-Bench 2.0 | 82.0% | Coming soon | Coming soon | | Vibe Code Bench | 69.85% | 4.06% | GPT-5.5 | | React Native Evals | 84.7% | Coming soon | Coming soon | | cursorBench31 | 59.2% | Coming soon | Coming soon | | cursorBench32 | 58.4% | Coming soon | Coming soon | | FrontierCode 1.1 Main | 43.0% | Coming soon | Coming soon | | LiveCodeBench (Vals) | 85.3% | 84.3% | GPT-5.5 | | SWE-bench (Vals) | 82.6% | 72.2% | GPT-5.5 | | LiveCodeBench Pro | Coming soon | 74.2% | Coming soon | | SWE-bench Verified | Coming soon | 76.7% | Coming soon | ### Multimodal & Grounded - Winner: Coming soon - GPT-5.5 public-lane score: 71.3 (#19/48) - Grok 4.20 public-lane score: 34.6 (#43/48) | Benchmark | GPT-5.5 | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | MMMU-Pro | 81.2% | 75.2% | GPT-5.5 | | MMMU-Pro w/ Python | 83.2% | Coming soon | Coming soon | | OfficeQA Pro | 54.1% | Coming soon | Coming soon | | CharXiv | Coming soon | 60.9% | Coming soon | | ERQA | Coming soon | 54.1% | Coming soon | | SimpleVQA | Coming soon | 57.4% | Coming soon | | MedXpertQA (MM) | Coming soon | 65.8% | Coming soon | ### Reasoning - Winner: Coming soon - GPT-5.5 public-lane score: 63.5 (#15/22) - Grok 4.20 public-lane score: 34.2 (Unranked · 2 rankable rows) | Benchmark | GPT-5.5 | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | MRCR v2 64K-128K | 83.1% | Coming soon | Coming soon | | MRCR v2 128K-256K | 87.5% | Coming soon | Coming soon | | ARC-AGI-2 | 85% | 53.3% | GPT-5.5 | | ARC-AGI-3 | 0.4% | 0.1% | GPT-5.5 | ### Knowledge - Winner: GPT-5.5 - GPT-5.5 public-lane score: 73.3 (Supported · #7/181) - Grok 4.20 public-lane score: 48.7 (Supported · #97/181) | Benchmark | GPT-5.5 | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | GPQA | 93.6% | Coming soon | Coming soon | | GPQA-D | 93.6% | 88.5% | GPT-5.5 | | HLE | 52.2% | Coming soon | Coming soon | | HLE w/o tools | 41.4% | 31.6% | GPT-5.5 | | GPQA Diamond (Vals) | 93.2% | 88.6% | GPT-5.5 | | MMLU-Pro (Vals) | 88.1% | 86.3% | GPT-5.5 | | HealthBench Hard | Coming soon | 20.3% | Coming soon | | MedXpertQA (Text) | Coming soon | 50.2% | Coming soon | ### Instruction Following - Winner: Coming soon - GPT-5.5 public-lane score: 92.9 (#7/120) - Grok 4.20 public-lane score: Coming soon ### Mathematics - Winner: Coming soon - GPT-5.5 public-lane score: 69.6 (Unranked · 3 rankable rows) - Grok 4.20 public-lane score: Coming soon | Benchmark | GPT-5.5 | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | FrontierMath (legacy) | 51.7% | Coming soon | Coming soon | | FrontierMath v2 (Tiers 1-3) | 51.700% | Coming soon | Coming soon | | FrontierMath v2 (Tier 4) | 35.400% | Coming soon | Coming soon | ## FAQ ### Which is better overall, GPT-5.5 or Grok 4.20? GPT-5.5 is ahead overall on BenchLM right now. ### Where is the biggest gap between GPT-5.5 and Grok 4.20? The widest category gap is in coding, where the averages are 67.7 for GPT-5.5 and 28.2 for Grok 4.20. ### How many benchmarks does GPT-5.5 cover on BenchLM? GPT-5.5 currently has 38 sourced benchmark scores on BenchLM. ### How many benchmarks does Grok 4.20 cover on BenchLM? Grok 4.20 currently has 23 sourced benchmark scores on BenchLM. ## Related Comparisons - [GPT-5.5 vs GPT-5.5 Pro](/compare/gpt-5-5-vs-gpt-5-5-pro) - [Grok 4.20 vs GPT-5.5 Pro](/compare/gpt-5-5-pro-vs-grok-4-20-beta) - [GPT-5.5 vs Grok 4.20 Multi-agent](/compare/gpt-5-5-vs-grok-4-20-multi-agent-beta) - [Grok 4.20 vs Grok 4.20 Multi-agent](/compare/grok-4-20-beta-vs-grok-4-20-multi-agent-beta) ## Explore More - [GPT-5.5 profile](/models/gpt-5-5) - [Grok 4.20 profile](/models/grok-4-20-beta) - [Compare Pricing](/llm-pricing) - [Alternative Finder](/tools/alternative-finder) - [LLM Selector](/tools/llm-selector) - [Overall Rankings](/best/overall)