Model comparison
Compare Claude Fable 5.1 and NVIDIA Nemotron 3 Ultra using the same provider-sourced text & reasoning rubric. No mystery score and no invented benchmark ranking.
Facts checked September 4, 2026
Set your usage. Your estimate updates as you type.
Example: 6,000 input tokens for 10 pages, plus a 500-token summary. Page lengths vary; adjust the numbers below.
One run sends your input to the model once and receives an answer. Tokens are pieces of text: input is what you send, output is the answer you receive.
Estimates exclude taxes, tools, cache storage/writes, free allowances and custom discounts. Image estimates cover output only, not prompt or reference-image charges. Quality modes differ by model. Unlisted settings are not treated as free.
| Model | Access | Estimated total (USD) |
|---|---|---|
| Claude Fable 5.1Anthropic | Anthropic | $0.085 |
| NVIDIA Nemotron 3 UltraNVIDIA | NVIDIA | No reviewed rate |
Quick take
Anthropic's frontier model for ambitious, long-running agentic and coding work, with strong vision and enterprise marketplace availability.
Confirm whether the default 30-day retention, fallback safeguards, and selected cloud marketplace meet your governance requirements before adoption.
NVIDIA's largest Nemotron 3 reasoning model for complex agents, coding, planning, tools, RAG, and million-token analysis.
Self-hosting Ultra is a substantial hardware project. Size the real context cache, concurrency, precision, and availability requirements before treating open weights as the cheaper route.
Compare the published facts
Values use each provider's own published units and limits. A blank means the provider did not publish a directly comparable value in the sources reviewed.
| Text & reasoning | Claude Fable 5.1 | NVIDIA Nemotron 3 Ultra |
|---|---|---|
| Context windowMaximum combined prompt and working context documented by the provider. | 1M tokens | Up to 1M tokens |
| Maximum outputProvider-published response limit, where available. | 128K tokens | Not separately published |
| Knowledge cutoffLatest reliable knowledge date explicitly published by the model provider. Search and connected tools can retrieve newer information but do not change the model's built-in cutoff. | June 2026 | Pretraining through Sep 2025; post-training through May 2026 |
| Input priceCurrent standard list price per million input tokens unless noted. | $10 / 1M | Free prototype or deployment cost |
| Output priceCurrent standard list price per million output tokens unless noted. | $50 / 1M | Free prototype or deployment cost |
| InputsMedia types accepted by the listed model endpoint. | Text, image, PDF | Text |
| Tools & agentsSelected native tools and agent-building capabilities, not an exhaustive list. | Tool use, agents, vision, coding workflows | Tool calling, agents, configurable reasoning budget |
How to choose
Start with the job you need to complete, then validate cost, access, and policy details on your exact provider route.
Fable requires 30-day retention for safety monitoring by default. Anthropic says enterprise data is not used for training without explicit permission; eligible enterprises can use EFS/customer-controlled storage or temporary zero-retention arrangements.
Downloaded weights can run in infrastructure the operator controls. NVIDIA's hosted prototype and partner endpoints are governed by their own trial, logging, retention, and deployment terms.
Provider and API links
Frequently asked questions
Claude Fable 5.1: Anthropic's frontier model for ambitious, long-running agentic and coding work, with strong vision and enterprise marketplace availability. NVIDIA Nemotron 3 Ultra: NVIDIA's largest Nemotron 3 reasoning model for complex agents, coding, planning, tools, RAG, and million-token analysis.
Consider Claude Fable 5.1 when your priority is Long-running autonomous projects. Consider NVIDIA Nemotron 3 Ultra when your priority is Complex long-running agents. Test both with your own data and provider route before committing.
No. This comparison aligns provider-published facts for the Text & reasoning category. It does not claim a universal winner or combine incompatible third-party benchmark scores.
