Model comparison
Claude Fable 5.1 vs Nemotron 3 Ultra
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 42.5 on the Noometry Index. Nemotron 3 Ultra costs 22× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.
Last verified . 29 shared benchmarks.
NVIDIASummary
- They share 29 benchmarks with published results for both. Claude Fable 5.1 scores higher in 9 categories and Nemotron 3 Ultra in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Fable 5.1 leads 89.6 to 35.3.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Fable 5.1 and 2% for Nemotron 3 Ultra.
- Nemotron 3 Ultra is cheaper at $0.50 / $2.20 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.
- Claude Fable 5.1 accepts more context: 1M tokens versus 262K.
- Nemotron 3 Ultra has downloadable open weights; the other is API-only.
Side by side
| Claude Fable 5.1 | Nemotron 3 Ultra | |
|---|---|---|
| Provider | Anthropic | NVIDIA |
| Noometry Index | 69.0 | 42.5 |
| Released | 2026-09-01 | 2026-06-04 |
| Weights | Proprietary | Open |
| Context window | 1M | 262K |
| Max output | 128K | 128K |
| Input $ / M tokens | $10 | $0.50 |
| Output $ / M tokens | $50 | $2.20 |
| Results tracked | 52 | 30 |
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Category by category
Coding Claude Fable 5.1 leads
Claude Fable 5.1: 74.7 (#1), Nemotron 3 Ultra: 38.1 (#182)
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| FrontierCode | 50.9% | 13.6% |
| SciCode | 63.1% | 40.3% |
| WeirdML | 92.9% | 43.5% |
| LMArena Coding | 1528 | 1468 |
| CursorBench | 51.8% | — |
| LMArena WebDev | 1744 | — |
| FrontierSWE | 56.3% | — |
| GSO | 88.2% | — |
| MirrorCode | 73.3% | — |
| ALE-Bench | 2,143 | — |
Agentic & Tool Use Claude Fable 5.1 leads
Claude Fable 5.1: 50.7 (#5), Nemotron 3 Ultra: 23.4 (#126)
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| APEX-Agents | 68.6% | 22.7% |
| 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), Nemotron 3 Ultra: 31.0 (#82)
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| CritPt | 31.1% | 3.1% |
| Chess Puzzles | 47% | 12% |
| LMArena Hard Prompts | 1526 | 1452 |
| Mystery Game Puzzles | 58% | 20% |
| DTBench | 97.6% | 90.1% |
| LMCA | 65.5% | 36.9% |
| Epoch Capabilities Index | 164.7 | 146.17 |
| ARC-AGI-2 | 90% | — |
| NYT Connections (extended) | 90% | — |
| ARC-AGI-1 | 97.5% | — |
| EBR-Bench | 57.1% | — |
Math Claude Fable 5.1 leads
Claude Fable 5.1: 89.6 (#4), Nemotron 3 Ultra: 35.3 (#187)
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 100% | 86.7% |
| ProofBench | 100% | 2% |
| LMArena Math | 1525 | 1457 |
| FrontierMath (Tiers 1-3) | 90.2% | — |
| FrontierMath Tier 4 | 87.8% | — |
| FrontierMath Erdős | 0% | — |
Knowledge Claude Fable 5.1 leads
Claude Fable 5.1: 69.6 (#6), Nemotron 3 Ultra: 52.5 (#61)
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| LMArena Expert | 1535 | 1472 |
| GPQA Diamond | — | 85.4% |
| Humanity's Last Exam | 46.5% | — |
| SimpleQA Verified | 70.8% | — |
Multimodal Not comparable
Claude Fable 5.1: 53.9 (#4), Nemotron 3 Ultra: —
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| 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), Nemotron 3 Ultra: 53.5 (#64)
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| LMArena Non-English | 1507 | 1427 |
| LMArena Chinese | 1586 | 1497 |
| LMArena French | 1525 | 1472 |
| LMArena German | 1500 | 1471 |
| LMArena Korean | 1534 | 1386 |
| LMArena Russian | 1521 | 1417 |
| LMArena Spanish | 1516 | 1454 |
| LMArena Japanese | 1543 | — |
Instruction Following Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#6), Nemotron 3 Ultra: 74.7 (#88)
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| LMArena Instruction Following | 1517 | 1418 |
Long Context Claude Fable 5.1 leads
Claude Fable 5.1: 46.7 (#20), Nemotron 3 Ultra: 43.9 (#81)
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| LMArena Longer Query | 1522 | 1437 |
Writing & Preference Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#2), Nemotron 3 Ultra: 66.3 (#36)
| Benchmark | Claude Fable 5.1 | Nemotron 3 Ultra |
|---|---|---|
| LMArena Text | 1510 | 1445 |
| LMArena Creative Writing | 1507 | 1398 |
| EQ-Bench Creative Writing | 2162 | 1692 |
| LMArena Multi-Turn | 1492 | 1411 |
Frequently asked questions
Is Claude Fable 5.1 better than Nemotron 3 Ultra?
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 42.5 on the Noometry Index. Nemotron 3 Ultra costs 22× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.
Which is cheaper, Claude Fable 5.1 or Nemotron 3 Ultra?
Nemotron 3 Ultra is cheaper. It lists at $0.50 per million input tokens and $2.20 per million output tokens; Claude Fable 5.1 lists at $10 and $50.
Is Claude Fable 5.1 or Nemotron 3 Ultra better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 38.1 in the Noometry coding category.
Which has the bigger context window?
Claude Fable 5.1 does, with 1M tokens against 262K.
How many benchmarks do Claude Fable 5.1 and Nemotron 3 Ultra share?
29 benchmarks have published results for both models. Claude Fable 5.1 has 52 scored results on Noometry and Nemotron 3 Ultra has 30.