Model comparison
Claude Fable 5.1 vs Step 2 16k Exp 202412
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 39.2 on the Noometry Index.
Last verified . 12 shared benchmarks.
StepFunSummary
- They share 12 benchmarks with published results for both. Claude Fable 5.1 scores higher in 8 categories and Step 2 16k Exp 202412 in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Fable 5.1 leads 89.6 to 36.3.
Side by side
| Claude Fable 5.1 | Step 2 16k Exp 202412 | |
|---|---|---|
| Provider | Anthropic | StepFun |
| Noometry Index | 69.0 | 39.2 |
| Released | 2026-09-01 | — |
| Weights | Proprietary | Proprietary |
| Context window | 1M | — |
| Max output | 128K | — |
| Input $ / M tokens | $10 | — |
| Output $ / M tokens | $50 | — |
| Results tracked | 52 | 12 |
Sponsored placements are available on pages like this one. Advertise on Noometry
Category by category
Coding Claude Fable 5.1 leads
Claude Fable 5.1: 74.7 (#1), Step 2 16k Exp 202412: 38.5 (#174)
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Coding | 1528 | 1316 |
| FrontierCode | 50.9% | — |
| CursorBench | 51.8% | — |
| LMArena WebDev | 1744 | — |
| FrontierSWE | 56.3% | — |
| SciCode | 63.1% | — |
| GSO | 88.2% | — |
| WeirdML | 92.9% | — |
| MirrorCode | 73.3% | — |
| ALE-Bench | 2,143 | — |
Agentic & Tool Use Not comparable
Claude Fable 5.1: 50.7 (#5), Step 2 16k Exp 202412: —
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| APEX-Agents | 68.6% | — |
| Remote Labor Index | 17.9% | — |
| GDP.pdf | 29.6% | — |
| Vending-Bench 2 | 5,422 | — |
Reasoning Claude Fable 5.1 leads
Claude Fable 5.1: 76.7 (#7), Step 2 16k Exp 202412: 25.9 (#142)
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Hard Prompts | 1526 | 1299 |
| ARC-AGI-2 | 90% | — |
| NYT Connections (extended) | 90% | — |
| ARC-AGI-1 | 97.5% | — |
| CritPt | 31.1% | — |
| Chess Puzzles | 47% | — |
| EBR-Bench | 57.1% | — |
| Mystery Game Puzzles | 58% | — |
| DTBench | 97.6% | — |
| LMCA | 65.5% | — |
| Epoch Capabilities Index | 164.7 | — |
Math Claude Fable 5.1 leads
Claude Fable 5.1: 89.6 (#4), Step 2 16k Exp 202412: 36.3 (#169)
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Math | 1525 | 1304 |
| FrontierMath (Tiers 1-3) | 90.2% | — |
| FrontierMath Tier 4 | 87.8% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | 100% | — |
| FrontierMath Erdős | 0% | — |
Knowledge Claude Fable 5.1 leads
Claude Fable 5.1: 69.6 (#6), Step 2 16k Exp 202412: 35.2 (#187)
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Expert | 1535 | 1279 |
| Humanity's Last Exam | 46.5% | — |
| SimpleQA Verified | 70.8% | — |
Multimodal Not comparable
Claude Fable 5.1: 53.9 (#4), Step 2 16k Exp 202412: —
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Vision | 1318 | — |
| Blueprint-Bench 2 | 41.9% | — |
| Furniture Assembly | 70% | — |
| LMArena Document | 1513 | — |
Multilingual Claude Fable 5.1 leads
Claude Fable 5.1: 59.1 (#3), Step 2 16k Exp 202412: 43.7 (#181)
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Non-English | 1507 | 1290 |
| LMArena Chinese | 1586 | 1331 |
| LMArena Russian | 1521 | 1324 |
| LMArena French | 1525 | — |
| LMArena German | 1500 | — |
| LMArena Japanese | 1543 | — |
| LMArena Korean | 1534 | — |
| LMArena Spanish | 1516 | — |
Instruction Following Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#6), Step 2 16k Exp 202412: 67.9 (#192)
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Instruction Following | 1517 | 1287 |
Long Context Claude Fable 5.1 leads
Claude Fable 5.1: 46.7 (#20), Step 2 16k Exp 202412: 39.7 (#170)
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Longer Query | 1522 | 1307 |
Writing & Preference Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#2), Step 2 16k Exp 202412: 52.3 (#173)
| Benchmark | Claude Fable 5.1 | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Text | 1510 | 1321 |
| LMArena Creative Writing | 1507 | 1328 |
| LMArena Multi-Turn | 1492 | 1292 |
| EQ-Bench Creative Writing | 2162 | — |
Frequently asked questions
Is Claude Fable 5.1 better than Step 2 16k Exp 202412?
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 39.2 on the Noometry Index.
Is Claude Fable 5.1 or Step 2 16k Exp 202412 better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 38.5 in the Noometry coding category.
How many benchmarks do Claude Fable 5.1 and Step 2 16k Exp 202412 share?
12 benchmarks have published results for both models. Claude Fable 5.1 has 52 scored results on Noometry and Step 2 16k Exp 202412 has 12.