Claude Fable 5.1 vs GPT-5.6 Terra
Detailed pricing comparison and cost analysis.
Updated September 2026
Cost Simulator
| Feature | Claude Fable 5.1 | GPT-5.6 Terra |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input Price (1M) | $10.00 | $2.00 |
| Output Price (1M) | $50.00 | $12.00 |
| Context Window | 1,000,000 | 1,000,000 |
Verdict
Claude Fable 5.1 costs $10.00 per 1M input tokens and $50.00 per 1M output tokens. GPT-5.6 Terra costs $2.00 per 1M input tokens and $12.00 per 1M output tokens. GPT-5.6 Terra is 80% cheaper on input tokens than Claude Fable 5.1. For output tokens, GPT-5.6 Terra is the more affordable option at $12.00/1M vs $50.00.
On context window, Claude Fable 5.1 supports 1,000,000 tokens — meaning it can fit more conversation history, documents, or code in a single request. This matters for RAG pipelines, long document analysis, and agentic workflows where context builds up over many turns.
When to choose Claude Fable 5.1
- ✓ You are already integrated with Anthropic
When to choose GPT-5.6 Terra
- ✓ You need the lowest input token cost ($ 2.00/1M)
- ✓ Your workload is output-heavy — GPT-5.6 Terra generates text cheaper
- ✓ You are already integrated with OpenAI
Use the calculator above to simulate your specific workload and find the exact break-even point. For most applications, the cheapest model is the one that minimises your total monthly bill given your input-to-output token ratio.
Frequently Asked Questions
Is Claude Fable 5.1 cheaper than GPT-5.6 Terra? ▼
GPT-5.6 Terra is cheaper on input tokens at $2.00/1M vs $10.00/1M for Claude Fable 5.1 — a 80% saving.
What is the context window of Claude Fable 5.1 vs GPT-5.6 Terra? ▼
Claude Fable 5.1 has a 1,000,000-token context window. GPT-5.6 Terra has a 1,000,000-token context window. Claude Fable 5.1 supports the larger context, suitable for longer documents and agentic workflows.
Which model is better: Claude Fable 5.1 or GPT-5.6 Terra? ▼
The best choice depends on your use case. For cost efficiency on input tokens, GPT-5.6 Terra is the cheaper option. For maximum context length, Claude Fable 5.1 supports 1,000,000 tokens. Use the comparison table above to find the right fit for your workload.