Model comparison
GPT-5-Codex vs Grok 3
Grok 3 is the stronger model overall, scoring 39.9 to 37.9 on the Noometry Index.
Last verified . 2 shared benchmarks.
Summary
- They share 2 benchmarks with published results for both. GPT-5-Codex scores higher in 3 categories and Grok 3 in 0 categories; one gap is clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5-Codex leads 30.9 to 13.7.
- The biggest single-benchmark swing is WeirdML: 54.5% for GPT-5-Codex and 37.2% for Grok 3.
Side by side
| GPT-5-Codex | Grok 3 | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 37.9 | 39.9 |
| Released | 2025-09-15 | 2025-04-09 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | — |
| Max output | 128K | — |
| Input $ / M tokens | $1.25 | — |
| Output $ / M tokens | $10 | — |
| Results tracked | 3 | 40 |
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Category by category
Coding Too close to call
GPT-5-Codex: 42.4 (#103), Grok 3: 41.9 (#115)
| Benchmark | GPT-5-Codex | Grok 3 |
|---|---|---|
| WeirdML | 54.5% | 37.2% |
| Aider Polyglot | — | 53.3% |
| LMArena Coding | — | 1432 |
Agentic & Tool Use Too close to call
GPT-5-Codex: 31.0 (#72), Grok 3: 30.5 (#76)
| Benchmark | GPT-5-Codex | Grok 3 |
|---|---|---|
| Terminal-Bench | 44.3% | — |
| BALROG | — | 29.5% |
Reasoning GPT-5-Codex leads
GPT-5-Codex: 30.9 (#83), Grok 3: 13.7 (#333)
| Benchmark | GPT-5-Codex | Grok 3 |
|---|---|---|
| Kagi LLM Benchmark | 70.3% | 61.3% |
| ARC-AGI-2 | — | 0% |
| SimpleBench | — | 36.1% |
| ARC-AGI-1 | — | 5.5% |
| LMArena Hard Prompts | — | 1434 |
| Epoch Capabilities Index | — | 138.33 |
Math Not comparable
GPT-5-Codex: —, Grok 3: 38.0 (#145)
| Benchmark | GPT-5-Codex | Grok 3 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | — | 55.6% |
| Omni-MATH | — | 46.4% |
| LMArena Math | — | 1391 |
| MATH Level 5 | — | 88.7% |
| FrontierMath (Feb 2025 set) | — | 3.8% |
| FrontierMath Tier 4 (v1) | — | 0% |
Knowledge Not comparable
GPT-5-Codex: —, Grok 3: 46.2 (#82)
| Benchmark | GPT-5-Codex | Grok 3 |
|---|---|---|
| GPQA Diamond | — | 75.8% |
| MMLU-Pro | — | 78.8% |
| Confabulations | — | 14.2% |
| Vectara Hallucination Rate | — | 5.8% |
| GPQA (HELM) | — | 65% |
| LMArena Expert | — | 1421 |
Multilingual Not comparable
GPT-5-Codex: —, Grok 3: 52.3 (#87)
| Benchmark | GPT-5-Codex | Grok 3 |
|---|---|---|
| LMArena Non-English | — | 1410 |
| LMArena Chinese | — | 1448 |
| LMArena French | — | 1460 |
| LMArena German | — | 1431 |
| LMArena Japanese | — | 1387 |
| LMArena Korean | — | 1373 |
| LMArena Russian | — | 1416 |
| LMArena Spanish | — | 1417 |
Instruction Following Not comparable
GPT-5-Codex: —, Grok 3: 75.0 (#73)
| Benchmark | GPT-5-Codex | Grok 3 |
|---|---|---|
| IFEval | — | 88.4% |
| LMArena Instruction Following | — | 1409 |
Long Context Not comparable
GPT-5-Codex: —, Grok 3: 38.7 (#192)
| Benchmark | GPT-5-Codex | Grok 3 |
|---|---|---|
| Fiction.LiveBench | — | 58.3% |
| LMArena Longer Query | — | 1439 |
Writing & Preference Not comparable
GPT-5-Codex: —, Grok 3: 55.8 (#141)
| Benchmark | GPT-5-Codex | Grok 3 |
|---|---|---|
| LMArena Text | — | 1426 |
| LMArena Creative Writing | — | 1414 |
| Short-Story Creative Writing | — | 76.4% |
| EQ-Bench Creative Writing | — | 1186 |
| WildBench | — | 84.9% |
| LMArena Multi-Turn | — | 1425 |
Frequently asked questions
Is GPT-5-Codex better than Grok 3?
Grok 3 is the stronger model overall, scoring 39.9 to 37.9 on the Noometry Index.
Is GPT-5-Codex or Grok 3 better for coding?
They score almost the same on coding (42.4 vs 41.9); test both on your own repository before choosing.
How many benchmarks do GPT-5-Codex and Grok 3 share?
2 benchmarks have published results for both models. GPT-5-Codex has 3 scored results on Noometry and Grok 3 has 40.