# GPT-5.6 Terra vs Grok 4.20 > Side-by-side benchmark comparison for GPT-5.6 Terra and Grok 4.20 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks. - Canonical page: https://benchlm.ai/compare/gpt-5-6-terra-vs-grok-4-20-beta - Last updated: September 24, 2026 - Shared sourced benchmarks: 11 - HTML indexing: indexable - Ranking lane: BenchAlign v5.7 ## Quick Verdict Pick GPT-5.6 Terra 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-5.6 Terra leads overall 72.58 to 59.66. - The clearest category separation is in multimodal & grounded, where the averages are 77.2 for GPT-5.6 Terra and 34.6 for Grok 4.20. - The biggest single benchmark swing is Terminal-Bench 2.1 (Vals) in Agentic, with scores of 77.5% and 44.2%. - 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-5.6 Terra | Grok 4.20 | |----------|----------|----------| | Creator | OpenAI | xAI | | Type | Proprietary | Proprietary | | Reasoning | Reasoning | Reasoning | | Context | 1.05M | 2M | | Overall Score | 72.58 | 59.66 | | Benchmarks Covered | 32 | 23 | | Pricing (input/output) | $2.00 / $12.00 | $1.25 / $2.50 | ## Category Breakdown ### Agentic - Winner: GPT-5.6 Terra - GPT-5.6 Terra public-lane score: 59.5 (Supported · #18/105) - Grok 4.20 public-lane score: 24.5 (Supported · #81/105) | Benchmark | GPT-5.6 Terra | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | Terminal-Bench 3.0 | 20.8% | Coming soon | Coming soon | | Terminal-Bench 2.1 | 87.4% | Coming soon | Coming soon | | BrowseComp | 87.5% | Coming soon | Coming soon | | OSWorld 2.0 | 50.2% | Coming soon | Coming soon | | CyberGym | 81.8% | Coming soon | Coming soon | | ExploitGym | 23.2% | Coming soon | Coming soon | | Toolathlon | 53.1% | Coming soon | Coming soon | | Terminal-Bench 2.1 (Vals) | 77.5% | 44.2% | GPT-5.6 Terra | | ApprenticeBench | 16% | Coming soon | Coming soon | | Terminal-Bench 2.0 | Coming soon | 47.1% | Coming soon | | DeepSearchQA | Coming soon | 62.8% | Coming soon | | Gert Labs | Coming soon | 38.36% | Coming soon | ### Coding - Winner: GPT-5.6 Terra - GPT-5.6 Terra public-lane score: 64.7 (Supported · #8/135) - Grok 4.20 public-lane score: 23.8 (Supported · #106/135) | Benchmark | GPT-5.6 Terra | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | SWE-bench Pro | 63.4% | 51.8% | GPT-5.6 Terra | | Terminal-Bench 2.1 | 87.4% | Coming soon | Coming soon | | DeepSWE | 69.6% | Coming soon | Coming soon | | FrontierCode 1.1 Extended | 55.8% | Coming soon | Coming soon | | cursorBench32 | 64.9% | Coming soon | Coming soon | | VulcanBench v3 | 87.0% | Coming soon | Coming soon | | LiveCodeBench (Vals) | 85.9% | 84.3% | GPT-5.6 Terra | | SWE-bench (Vals) | 95.4% | 72.2% | GPT-5.6 Terra | | LiveCodeBench Pro | Coming soon | 74.2% | Coming soon | | SWE-bench Verified | Coming soon | 76.7% | Coming soon | | Vibe Code Bench | Coming soon | 4.06% | Coming soon | ### Reasoning - Winner: Not comparable - GPT-5.6 Terra public-lane score: 65.4 (#12/19) - Grok 4.20 public-lane score: 41.1 (Unranked · 2 rankable rows) | Benchmark | GPT-5.6 Terra | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | ARC-AGI-2 | 83.9% | 53.3% | GPT-5.6 Terra | | ARC-AGI-3 | 0.8% | 0.1% | GPT-5.6 Terra | ### Multimodal & Grounded - Winner: Directional only - GPT-5.6 Terra public-lane score: 77.2 (#16/50) - Grok 4.20 public-lane score: 34.6 (#45/50) | Benchmark | GPT-5.6 Terra | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | MMMU-Pro | 80.7% | 75.2% | GPT-5.6 Terra | | MMMU-Pro w/ Python | 82% | 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 | ### Knowledge - Winner: GPT-5.6 Terra - GPT-5.6 Terra public-lane score: 71.1 (Supported · #9/158) - Grok 4.20 public-lane score: 51 (Supported · #55/158) | Benchmark | GPT-5.6 Terra | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | GPQA | 92.9% | Coming soon | Coming soon | | GPQA-D | 92.9% | 88.5% | GPT-5.6 Terra | | HLE-Verified | 51.1% | Coming soon | Coming soon | | LABBench2 | 81.2% | Coming soon | Coming soon | | HealthBench Professional | 57.7% | Coming soon | Coming soon | | HealthBench Hard | 32.7% | 20.3% | GPT-5.6 Terra | | GPQA Diamond (Vals) | 90.9% | 88.6% | GPT-5.6 Terra | | MMLU-Pro (Vals) | 86.7% | 86.3% | GPT-5.6 Terra | | HLE w/o tools | Coming soon | 31.6% | Coming soon | | MedXpertQA (Text) | Coming soon | 50.2% | Coming soon | ### Instruction Following - Winner: Not comparable - GPT-5.6 Terra public-lane score: 85.7 (#35/124) - Grok 4.20 public-lane score: Coming soon ### Mathematics - Winner: Not comparable - GPT-5.6 Terra public-lane score: 96.8 (Unranked · 3 rankable rows) - Grok 4.20 public-lane score: Coming soon | Benchmark | GPT-5.6 Terra | Grok 4.20 | Winner | |-----------|-----------|-----------|--------| | FrontierMath (legacy) | 84.9% | Coming soon | Coming soon | | FrontierMath v2 (Tiers 1-3) | 84.900% | Coming soon | Coming soon | | FrontierMath v2 (Tier 4) | 68.300% | Coming soon | Coming soon | ## FAQ ### Which is better overall, GPT-5.6 Terra or Grok 4.20? GPT-5.6 Terra is ahead overall on BenchLM right now. ### Where is the biggest gap between GPT-5.6 Terra and Grok 4.20? The widest category gap is in multimodal & grounded, where the averages are 77.2 for GPT-5.6 Terra and 34.6 for Grok 4.20. ### How many benchmarks does GPT-5.6 Terra cover on BenchLM? GPT-5.6 Terra currently has 32 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-5.6 Terra vs GPT-5.6 Sol](/compare/gpt-5-6-sol-vs-gpt-5-6-terra) - [Grok 4.20 vs GPT-5.6 Sol](/compare/gpt-5-6-sol-vs-grok-4-20-beta) - [GPT-5.6 Terra vs GPT-5.6 Luna](/compare/gpt-5-6-luna-vs-gpt-5-6-terra) - [Grok 4.20 vs GPT-5.6 Luna](/compare/gpt-5-6-luna-vs-grok-4-20-beta) ## Explore More - [GPT-5.6 Terra profile](/models/gpt-5-6-terra) - [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)