Model comparison
GPT-5.1-Codex vs Grok 4.20 (Non-Reasoning)
Grok 4.20 (Non-Reasoning) is the stronger model overall, scoring 48.5 to 38.2 on the Noometry Index.
Last verified . 4 shared benchmarks.
Summary
- They share 4 benchmarks with published results for both. GPT-5.1-Codex scores higher in 1 category and Grok 4.20 (Non-Reasoning) in 2 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in math, where Grok 4.20 (Non-Reasoning) leads 48.0 to 29.3.
- The biggest single-benchmark swing is ProofBench: 9% for GPT-5.1-Codex and 14% for Grok 4.20 (Non-Reasoning).
- Grok 4.20 (Non-Reasoning) is cheaper at $1.25 / $2.50 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- Grok 4.20 (Non-Reasoning) accepts more context: 1M tokens versus 400K.
Side by side
| GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 38.2 | 48.5 |
| Released | 2025-11-12 | 2026-02-17 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 1M |
| Max output | 128K | 30K |
| Input $ / M tokens | $1.25 | $1.25 |
| Output $ / M tokens | $10 | $2.50 |
| Results tracked | 6 | 46 |
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Category by category
Coding Too close to call
GPT-5.1-Codex: 41.7 (#107), Grok 4.20 (Non-Reasoning): 41.8 (#104)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena WebDev | 1337 | 1374 |
| ALE-Bench | 1,245 | 1,150 |
| SWE-bench Verified (bash only) | 66% | — |
| WeirdML | — | 52.3% |
| LMArena Coding | — | 1458 |
Agentic & Tool Use GPT-5.1-Codex leads
GPT-5.1-Codex: 37.8 (#32), Grok 4.20 (Non-Reasoning): 34.3 (#43)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| Terminal-Bench | 60.4% | 57.3% |
| τ²-bench Banking | — | 18% |
| LMArena Search | — | 1189 |
| METR Time Horizons | 70.8% | — |
| Vending-Bench 2 | — | 4,663 |
Reasoning Not comparable
GPT-5.1-Codex: —, Grok 4.20 (Non-Reasoning): 52.2 (#30)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| ARC-AGI-2 | — | 65.1% |
| Kagi LLM Benchmark | — | 75% |
| NYT Connections (extended) | — | 85.4% |
| ARC-AGI-1 | — | 89.5% |
| Chess Puzzles | — | 24% |
| Thematic Generalization | — | 63.8% |
| LMArena Hard Prompts | — | 1451 |
| DTBench | — | 90.1% |
| LMCA | — | 38.7% |
| Epoch Capabilities Index | — | 152.01 |
| ForecastBench | — | 61.4 |
Math Grok 4.20 (Non-Reasoning) leads
GPT-5.1-Codex: 29.3 (#218), Grok 4.20 (Non-Reasoning): 48.0 (#54)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| ProofBench | 9% | 14% |
| FrontierMath (Tiers 1-3) | — | 44.9% |
| FrontierMath Tier 4 | — | 17.1% |
| OTIS Mock AIME 2024-2025 | — | 92.2% |
| LMArena Math | — | 1455 |
Knowledge Not comparable
GPT-5.1-Codex: —, Grok 4.20 (Non-Reasoning): 52.8 (#54)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| GPQA Diamond | — | 89.3% |
| SimpleQA Verified | — | 30.2% |
| LMArena Expert | — | 1440 |
Multimodal Not comparable
GPT-5.1-Codex: —, Grok 4.20 (Non-Reasoning): 33.2 (#88)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Vision | — | 1263 |
| Blueprint-Bench 2 | — | 0% |
| LMArena Document | — | 1416 |
Multilingual Not comparable
GPT-5.1-Codex: —, Grok 4.20 (Non-Reasoning): 54.7 (#38)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Non-English | — | 1440 |
| LMArena Chinese | — | 1481 |
| LMArena French | — | 1477 |
| LMArena German | — | 1463 |
| LMArena Japanese | — | 1450 |
| LMArena Korean | — | 1417 |
| LMArena Russian | — | 1457 |
| LMArena Spanish | — | 1442 |
Instruction Following Not comparable
GPT-5.1-Codex: —, Grok 4.20 (Non-Reasoning): 75.0 (#79)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Instruction Following | — | 1420 |
Long Context Not comparable
GPT-5.1-Codex: —, Grok 4.20 (Non-Reasoning): 45.4 (#33)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| CL-bench | — | 22.2% |
| CL-bench Life | — | 11.9% |
| LMArena Longer Query | — | 1436 |
Writing & Preference Not comparable
GPT-5.1-Codex: —, Grok 4.20 (Non-Reasoning): 65.9 (#42)
| Benchmark | GPT-5.1-Codex | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Text | — | 1451 |
| LMArena Creative Writing | — | 1439 |
| EQ-Bench Creative Writing | — | 1574 |
| LMArena Multi-Turn | — | 1456 |
Frequently asked questions
Is GPT-5.1-Codex better than Grok 4.20 (Non-Reasoning)?
Grok 4.20 (Non-Reasoning) is the stronger model overall, scoring 48.5 to 38.2 on the Noometry Index.
Which is cheaper, GPT-5.1-Codex or Grok 4.20 (Non-Reasoning)?
Grok 4.20 (Non-Reasoning) is cheaper. It lists at $1.25 per million input tokens and $2.50 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.
Is GPT-5.1-Codex or Grok 4.20 (Non-Reasoning) better for coding?
They score almost the same on coding (41.7 vs 41.8); test both on your own repository before choosing.
Which has the bigger context window?
Grok 4.20 (Non-Reasoning) does, with 1M tokens against 400K.
How many benchmarks do GPT-5.1-Codex and Grok 4.20 (Non-Reasoning) share?
4 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Grok 4.20 (Non-Reasoning) has 46.