Model comparison
GPT-5.1-Codex vs Step 3
Step 3 is the stronger model overall, scoring 39.9 to 38.2 on the Noometry Index.
Last verified . 0 shared benchmarks.
StepFunSummary
- The widest gap is in math, where Step 3 leads 34.9 to 29.3.
- Step 3 has downloadable open weights; the other is API-only.
Side by side
| GPT-5.1-Codex | Step 3 | |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 38.2 | 39.9 |
| Released | 2025-11-12 | — |
| Weights | Proprietary | Open |
| Context window | 400K | — |
| Max output | 128K | — |
| Input $ / M tokens | $1.25 | — |
| Output $ / M tokens | $10 | — |
| Results tracked | 6 | 17 |
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Category by category
Coding GPT-5.1-Codex leads
GPT-5.1-Codex: 41.7 (#107), Step 3: 39.5 (#144)
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| SWE-bench Verified (bash only) | 66% | — |
| LMArena WebDev | 1337 | — |
| LMArena Coding | — | 1367 |
| ALE-Bench | 1,245 | — |
Agentic & Tool Use Not comparable
GPT-5.1-Codex: 37.8 (#32), Step 3: —
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| METR Time Horizons | 70.8% | — |
Reasoning Not comparable
GPT-5.1-Codex: —, Step 3: 27.6 (#102)
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| Kagi LLM Benchmark | — | 62.3% |
| LMArena Hard Prompts | — | 1355 |
Math Step 3 leads
GPT-5.1-Codex: 29.3 (#218), Step 3: 34.9 (#148)
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| ProofBench | 9% | — |
| LMArena Math | — | 1366 |
Knowledge Not comparable
GPT-5.1-Codex: —, Step 3: 36.2 (#161)
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| LMArena Expert | — | 1333 |
Multimodal Not comparable
GPT-5.1-Codex: —, Step 3: 34.9 (#81)
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| LMArena Vision | — | 1176 |
Multilingual Not comparable
GPT-5.1-Codex: —, Step 3: 46.5 (#154)
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| LMArena Non-English | — | 1327 |
| LMArena Chinese | — | 1396 |
| LMArena German | — | 1371 |
| LMArena Korean | — | 1271 |
| LMArena Russian | — | 1331 |
| LMArena Spanish | — | 1372 |
Instruction Following Not comparable
GPT-5.1-Codex: —, Step 3: 70.6 (#159)
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| LMArena Instruction Following | — | 1332 |
Long Context Not comparable
GPT-5.1-Codex: —, Step 3: 40.3 (#152)
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| LMArena Longer Query | — | 1326 |
Writing & Preference Not comparable
GPT-5.1-Codex: —, Step 3: 54.5 (#146)
| Benchmark | GPT-5.1-Codex | Step 3 |
|---|---|---|
| LMArena Text | — | 1351 |
| LMArena Creative Writing | — | 1322 |
| LMArena Multi-Turn | — | 1340 |
Frequently asked questions
Is GPT-5.1-Codex better than Step 3?
Step 3 is the stronger model overall, scoring 39.9 to 38.2 on the Noometry Index.
Is GPT-5.1-Codex or Step 3 better for coding?
GPT-5.1-Codex scores higher on coding benchmarks: 41.7 versus 39.5 in the Noometry coding category.
How many benchmarks do GPT-5.1-Codex and Step 3 share?
0 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Step 3 has 17.