Model comparison
GPT-5 Nano vs Step 3
Step 3 is the stronger model overall, scoring 39.9 to 33.4 on the Noometry Index.
Last verified . 17 shared benchmarks.
StepFunSummary
- They share 17 benchmarks with published results for both. GPT-5 Nano scores higher in 1 category and Step 3 in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Step 3 leads 54.5 to 39.4.
- Step 3 has downloadable open weights; the other is API-only.
Side by side
| GPT-5 Nano | Step 3 | |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 33.4 | 39.9 |
| Released | 2025-08-07 | — |
| Weights | Proprietary | Open |
| Context window | 400K | — |
| Max output | 128K | — |
| Input $ / M tokens | $0.05 | — |
| Output $ / M tokens | $0.40 | — |
| Results tracked | 48 | 17 |
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Category by category
Coding Step 3 leads
GPT-5 Nano: 33.3 (#248), Step 3: 39.5 (#144)
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| LMArena Coding | 1351 | 1367 |
| SWE-bench Verified (bash only) | 34.8% | — |
| WeirdML | 38.1% | — |
| ALE-Bench | 718.67 | — |
Agentic & Tool Use Not comparable
GPT-5 Nano: 25.6 (#99), Step 3: —
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| Terminal-Bench | 21.8% | — |
| Berkeley Function Calling Leaderboard | 51.5% | — |
Reasoning Step 3 leads
GPT-5 Nano: 16.4 (#291), Step 3: 27.6 (#102)
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| Kagi LLM Benchmark | 62.2% | 62.3% |
| LMArena Hard Prompts | 1329 | 1355 |
| ARC-AGI-2 | 2.6% | — |
| ARC-AGI-1 | 20.7% | — |
| Chess Puzzles | 27% | — |
| Mystery Game Puzzles | 9% | — |
| DTBench | 62.7% | — |
| LMCA | 7.9% | — |
| Epoch Capabilities Index | 139.39 | — |
| ForecastBench | 59.1 | — |
Math Step 3 leads
GPT-5 Nano: 29.1 (#221), Step 3: 34.9 (#148)
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| LMArena Math | 1318 | 1366 |
| FrontierMath (Tiers 1-3) | 20% | — |
| FrontierMath Tier 4 | 2.4% | — |
| OTIS Mock AIME 2024-2025 | 81.1% | — |
| ProofBench | 12% | — |
| Omni-MATH | 54.6% | — |
| MATH Level 5 | 95.2% | — |
| FrontierMath (Feb 2025 set) | 8.3% | — |
| FrontierMath Tier 4 (v1) | 2.1% | — |
Knowledge Too close to call
GPT-5 Nano: 35.8 (#166), Step 3: 36.2 (#161)
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| LMArena Expert | 1321 | 1333 |
| GPQA Diamond | 69.4% | — |
| SimpleQA Verified | 11.7% | — |
| MMLU-Pro | 77.8% | — |
| Vectara Hallucination Rate | 10.5% | — |
| GPQA (HELM) | 67.9% | — |
Multimodal Step 3 leads
GPT-5 Nano: 30.7 (#102), Step 3: 34.9 (#81)
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| LMArena Vision | 1159 | 1176 |
| VPCT | 37.2% | — |
Multilingual Step 3 leads
GPT-5 Nano: 45.5 (#167), Step 3: 46.5 (#154)
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| LMArena Non-English | 1313 | 1327 |
| LMArena Chinese | 1355 | 1396 |
| LMArena German | 1329 | 1371 |
| LMArena Korean | 1269 | 1271 |
| LMArena Russian | 1296 | 1331 |
| LMArena Spanish | 1360 | 1372 |
Instruction Following GPT-5 Nano leads
GPT-5 Nano: 75.2 (#72), Step 3: 70.6 (#159)
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| LMArena Instruction Following | 1306 | 1332 |
| IFEval | 93.2% | — |
Long Context Step 3 leads
GPT-5 Nano: 31.3 (#275), Step 3: 40.3 (#152)
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| LMArena Longer Query | 1313 | 1326 |
| Fiction.LiveBench | 44.4% | — |
Writing & Preference Step 3 leads
GPT-5 Nano: 39.4 (#244), Step 3: 54.5 (#146)
| Benchmark | GPT-5 Nano | Step 3 |
|---|---|---|
| LMArena Text | 1320 | 1351 |
| LMArena Creative Writing | 1250 | 1322 |
| LMArena Multi-Turn | 1311 | 1340 |
| EQ-Bench Creative Writing | 705 | — |
| WildBench | 80.6% | — |
Frequently asked questions
Is GPT-5 Nano better than Step 3?
Step 3 is the stronger model overall, scoring 39.9 to 33.4 on the Noometry Index.
Is GPT-5 Nano or Step 3 better for coding?
Step 3 scores higher on coding benchmarks: 39.5 versus 33.3 in the Noometry coding category.
How many benchmarks do GPT-5 Nano and Step 3 share?
17 benchmarks have published results for both models. GPT-5 Nano has 48 scored results on Noometry and Step 3 has 17.