Closest alternatives
The closest alternative inside Anthropic's own range is Claude Opus 5 at $5 per 1M input and $25 per 1M output, which scores 52.3% on Terminal-Bench 4.0 against 55.8% for Fable 5.1 and therefore delivers more benchmark points per dollar. Outside Anthropic, GPT-5.6 Sol is the only model Anthropic benchmarked directly. For teams optimising on cost rather than peak capability, open-weight models with 1M-token context windows serve much of the same workload.
| Model | Input $/1M | Output $/1M | Context | Routable via OneInfer | Terminal-Bench 4.0 |
|---|---|---|---|---|---|
| Claude Opus 5 | $5.00 | $25.00 | 1M | Yes | 52.3% |
| Claude Sonnet 5 | $2.00 | $10.00 | — | Yes | not published |
| GPT-5.6 Sol | $5.00 | $30.00 | — | No | 37.3% |
| Kimi K3 | $3.00 | $15.00 | 1M | Yes | not published |
| GLM-5.3 | $1.40 | $4.40 | — | Yes | not published |
| DeepSeek V4 Pro | $0.435 | $0.87 off-peak | — | Yes | not published |
Open-weight alternatives
Open-weight alternatives to Claude Fable 5.1 include Kimi K3 at 2.8 trillion parameters with a 1M-token context and DeepSeek V4 Pro under the MIT licence on its prior checkpoint. Claude Fable 5.1 has no open-weight equivalent. Frame these as substitutes for the workload, not equivalents for the model.
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If your workload re-reads a large cached prefix (long-running agents, multi-turn coding), Claude Fable 5.1 wins on cost. If your workload is short, single-turn, and cache-light, Claude Opus 5 or Kimi K3 deliver comparable quality at half the price. If you need peak capability on agentic scientific research, Claude Fable 5.1 is the only Anthropic model that published scores above 50% on Terminal-Bench-Science 0.1.
Frequently asked questions
What are the alternatives to Claude Fable 5.1?
The closest alternative inside Anthropic's own range is Claude Opus 5 at $5 per 1M input and $25 per 1M output. Outside Anthropic, GPT-5.6 Sol is the only model Anthropic benchmarked directly. For teams optimising on cost rather than peak capability, Kimi K3 at $3 and $15 per 1M, GLM-5.3 at $1.40 and $4.40, and DeepSeek V4 Pro at $0.435 and $0.87 off-peak all serve much of the same workload.
Put Claude Fable 5.1 to work
Fund a controlled evaluation, start with a prepared prompt, and measure quality and cost on your own workload.