Cheaper overall
gpt-5.6-terra
78% lower blended rate
Higher benchmark scores
Claude Fable 5.1
leads on 10 of 11 figures
Bigger context window
gpt-5.6-terra
1,050,000 vs 1,000,000 tokens
Cheaper cached input
gpt-5.6-terra
$0.20 vs $0.25, 20% less
Where each one wins
Claude Fable 5.1
- Higher overall intelligence (Intelligence Index) 53.4 vs 42.1
- Higher coding ability (Coding Index) 81.6 vs 76.7
- Higher multi-step tool use (Agentic Index) 57.9 vs 43.2
- Ahead on 7 more benchmark figures
gpt-5.6-terra
- Cheaper input tokens $2.00 vs $10.00, 80% less
- Cheaper output tokens $12.00 vs $50.00, 76% less
- Cheaper cached input $0.20 vs $0.25, 20% less
- Cheaper on all four workloads
- Larger context window 1,050,000 tokens
- Higher physics research reasoning (CritPt) 30 vs 29.7
- Offers Flex and Priority pricing not listed for Claude Fable 5.1
What four workloads cost
One run, and the same run a thousand times.
gpt-5.6-terra is cheaper on all four workloads, by much the same margin each time — about 3.8 times, from $0.0080 against $0.0350 on a chat turn to $1.65 against $4.15 on a long document.
| Workload | Claude Fable 5.1 | gpt-5.6-terra | ×1,000 | Difference |
|---|---|---|---|---|
| Chat turn 1,000 in / 500 out | $0.0350 | $0.0080 | $35.00 / $8.00 | gpt-5.6-terra is 77% cheaper |
| RAG answer 10,000 in / 800 out | $0.1400 | $0.0296 | $140.00 / $29.60 | gpt-5.6-terra is 79% cheaper |
| Agent loop 32,000 in / 700 out × 20 calls | $1.25 | $0.3680 | $1,250.00 / $368.00 | gpt-5.6-terra is 71% cheaper |
| Long document 400,000 in / 3,000 out | $4.15 | $1.65 | $4,150.00 / $1,654.00 | gpt-5.6-terra is 60% cheaper |
Price per 1M tokens
Above 272,000 input tokens the rates change, and the new rate applies to the whole request, not just the tokens past that point: gpt-5.6-terra's input goes from $2.00 to $4.00. It does not change which of the two is cheaper.
| Context band | Price | Claude Fable 5.1 | gpt-5.6-terra | Difference |
|---|---|---|---|---|
| Prompts up to 272,000 tokens | Input | $10.00 | $2.00 | gpt-5.6-terra is 80% cheaper |
| Prompts up to 272,000 tokens | Cached input | $0.25 | $0.20 | gpt-5.6-terra is 20% cheaper |
| Prompts up to 272,000 tokens | Output | $50.00 | $12.00 | gpt-5.6-terra is 76% cheaper |
| Prompts over 272,000 tokens | Input | $10.00 | $4.00 | gpt-5.6-terra is 60% cheaper |
| Prompts over 272,000 tokens | Cached input | $0.25 | $0.40 | Claude Fable 5.1 is 38% cheaper |
| Prompts over 272,000 tokens | Output | $50.00 | $18.00 | gpt-5.6-terra is 64% cheaper |
Blended: Claude Fable 5.1 $20.00, gpt-5.6-terra $4.50 per 1M — one rate at 3:1 input to output, for comparing two models at a glance.
Claude Fable 5.1 priced by Anthropic, gpt-5.6-terra by OpenAI. Standard tier, pay-as-you-go.
Other pricing tiers
Both models offer Batch, worth up to 50% off their standard rates, and the cheaper model is the same one on every tier — so the tier you buy changes the bill rather than the choice. Only gpt-5.6-terra lists Flex and Priority, at up to 50% off its own standard rate; Claude Fable 5.1 offers none of them.
Every tier either model sells is here, so this is the whole price sheet. A saving is measured against that model's own standard rate — how we read tiers.
| Tier | Claude Fable 5.1 | gpt-5.6-terra | Cheaper |
|---|---|---|---|
| Batch | $5.00 in / $25.00 out 50% off Standard | $1.00 in / $6.00 out 50% off Standard | gpt-5.6-terra |
| Flex only on gpt-5.6-terra | Not offered | $1.00 in / $6.00 out 50% off Standard | — |
| Priority only on gpt-5.6-terra | Not offered | $4.00 in / $24.00 out | — |
Benchmarks
They share 11 figures: Claude Fable 5.1 leads on 10, gpt-5.6-terra on 1. The widest gap is 20.4 points, on factual accuracy (Omniscience Accuracy).
Overall intelligence
Intelligence Index — Overall intelligence across reasoning, knowledge & math evals
Claude Fable 5.1 ahead by 11.3
Coding ability
Coding Index — Coding ability across software-engineering evals
Claude Fable 5.1 ahead by 4.9
Multi-step tool use
Agentic Index — Tool use & multi-step agent task performance
Claude Fable 5.1 ahead by 14.7
Graduate-level science
GPQA Diamond — Graduate-level questions in biology, chemistry & physics
Claude Fable 5.1 ahead by 1.2
Expert-exam performance
Humanity's Last Exam — Expert-level questions across many academic domains
Claude Fable 5.1 ahead by 16.2
Long-context reasoning
AA-LCR — Long-context reasoning across large inputs
Claude Fable 5.1 ahead by 2.3
Scientific coding
SciCode — Research-level scientific coding tasks
Claude Fable 5.1 ahead by 8.1
Physics research reasoning
CritPt — Unpublished physics research reasoning problems
gpt-5.6-terra ahead by 0.3
Real-world task performance
GDPval — Economically valuable, real-world knowledge work
Claude Fable 5.1 ahead by 15.1
Factual accuracy
Omniscience Accuracy — Breadth of factual knowledge across domains
Claude Fable 5.1 ahead by 20.4
Answer reliability
Omniscience Non-Hallucination — How reliably the model avoids fabricated answers
Claude Fable 5.1 ahead by 15.3
Each figure is that model's best published run, with the effort level named beside it — where these scores come from.
Specifications
gpt-5.6-terra holds 50,000 more input tokens in one request. Only Claude Fable 5.1 lists computer use.
| Specification | Claude Fable 5.1 | gpt-5.6-terra |
|---|---|---|
| Context window | 1,000,000 tokens | 1,050,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Takes in | Text, image, file | Text, image, file |
| Puts out | Text | Text |
| Knowledge cutoff | 30 Jun 2026 | 16 Feb 2026 |
| Released | 1 Sep 2026 | 9 Jul 2026 |
| Status | Active | Active |
| Sold by | Anthropic | OpenAI, Perplexity |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Web search | Not listed | Not listed |
| Prompt caching | Yes | Yes |
| Code execution | Yes | Yes |
| Computer use | Yes | Not listed |
| Open weights | Not listed | Not listed |
| Reasoning | Yes | Yes |
FAQs
- Is Claude Fable 5.1 cheaper than gpt-5.6-terra?
- No — the other way round. A 1,000-token prompt with a 500-token reply costs $0.0350 on Claude Fable 5.1 and $0.0080 on gpt-5.6-terra, and the same model is cheaper on every workload on this page.
- How much do Claude Fable 5.1 and gpt-5.6-terra cost per 1M tokens?
- Claude Fable 5.1 costs $10.00 for input and $50.00 for output. gpt-5.6-terra costs $2.00 and $12.00. Standard pay-as-you-go rates, as of 1 Sep 2026.
- Which is better, Claude Fable 5.1 or gpt-5.6-terra?
- On published benchmarks, Claude Fable 5.1. It leads on 10 of the 11 figures both models report, including overall intelligence (Intelligence Index), where it scores 53.4 against 42.1.
- Is Batch pricing cheaper for Claude Fable 5.1 or gpt-5.6-terra?
- Batch input costs $5.00 on Claude Fable 5.1 and $1.00 on gpt-5.6-terra, 50% below the standard rate on both.
- Does Claude Fable 5.1 or gpt-5.6-terra have a bigger context window?
- gpt-5.6-terra, at 1,050,000 tokens against 1,000,000. That is 50,000 more input tokens in a single request.