Claude Fable 5.1 vs GPT-5.6 Luna: Release Comparison

Comparison of the Claude Fable 5.1 and GPT-5.6 Luna releases: 5 and 6 models respectively, each with different intelligence, performance, and pricing characteristics. Below is a comparison of the key metrics across all 11 models.

  • For intelligence, Claude Fable 5.1 scores highest: Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) at 66, against GPT-5.6 Luna (max) at 52 for GPT-5.6 Luna.
  • For output speed, GPT-5.6 Luna is fastest: GPT-5.6 Luna (max) at 126 t/s, against Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) at 66 t/s for Claude Fable 5.1.
  • For cost per task, GPT-5.6 Luna is cheapest: GPT-5.6 Luna (low) at $0.01, against Claude Fable 5.1 (Adaptive Reasoning, Low Effort, Default Fallback) at $0.77 for Claude Fable 5.1.

Releases compared

AnthropicClaude Fable 5.1OpenAIGPT-5.6 Luna

Intelligence

Artificial Analysis Intelligence Index

Artificial Analysis Intelligence Index v4.1.1 incorporates 9 evaluations: GDPval-AA v2, 𝜏³-Banking, Terminal-Bench v2.1, SciCode, Humanity's Last Exam, GPQA Diamond, CritPt, AA-Omniscience, AA-LCR

Artificial Analysis Intelligence Index v4.1.1 includes: GDPval-AA v2, 𝜏³-Banking, Terminal-Bench v2.1, SciCode, Humanity's Last Exam, GPQA Diamond, CritPt, AA-Omniscience, AA-LCR. See Intelligence Index methodology for further details, including a breakdown of each evaluation and how we run them.

Intelligence Index vs. Cost per Intelligence Index Task

Artificial Analysis Intelligence Index · Weighted average cost (USD) per Artificial Analysis Intelligence Index task
Most attractive quadrant
Claude Fable 5.1
GPT-5.6 Luna
Pareto line

Weighted average cost per Intelligence Index task. Each evaluation’s cost is calculated from input, cache hit, cache write, reasoning, and answer token prices, divided by task count, and weighted by its Intelligence Index weight.

Artificial Analysis Intelligence Index v4.1.1 includes: GDPval-AA v2, 𝜏³-Banking, Terminal-Bench v2.1, SciCode, Humanity's Last Exam, GPQA Diamond, CritPt, AA-Omniscience, AA-LCR. See Intelligence Index methodology for further details, including a breakdown of each evaluation and how we run them.

Cost

Cost per Intelligence Index Task

Weighted average cost (USD) per Artificial Analysis Intelligence Index task, segmented by token type. Lower is better

Weighted average cost per Intelligence Index task. Each evaluation’s cost is calculated from input, cache hit, cache write, reasoning, and answer token prices, divided by task count, and weighted by its Intelligence Index weight.

Speed & Latency

Output Speed

Output tokens per second · Higher is better

Tokens per second received while the model is generating tokens (ie. after first chunk has been received from the API for models which support streaming).

Figures represent performance of the model's first-party API (e.g. OpenAI for o1) or the median across providers where a first-party API is not available (e.g. Meta's Llama models).

Capability Scores

Capability Indices

Measures the performance of models on specific capabilities and industries
Agentic Index

Measures performance in agentic workflows, focusing on behaviors like tool use, planning, autonomy, and complex problem solving.

Finance & Accounting Index

Incorporates 5 evaluations: AA-Omniscience, GDPval-AA v2, Humanity's Last Exam, 𝜏³-Banking, AA-LCR · Higher is better

Strategy & Ops Index

Incorporates 4 evaluations: AA-Omniscience, GDPval-AA v2, 𝜏³-Banking, AA-LCR · Higher is better

Legal Index

Incorporates 5 evaluations: AA-Omniscience, GDPval-AA v2, AA-LCR, 𝜏³-Banking, Humanity's Last Exam · Higher is better

Healthcare & Medical Index

Incorporates 5 evaluations: AA-Omniscience, GDPval-AA v2, MLCR-AA, Humanity's Last Exam, 𝜏³-Banking · Higher is better

Engineering Index

Incorporates 6 evaluations: AA-Omniscience, Humanity's Last Exam, GPQA Diamond, CritPt, GDPval-AA v2, Terminal-Bench v2.1 · Higher is better

Economics Index

Incorporates 4 evaluations: AA-Omniscience, Humanity's Last Exam, GDPval-AA v2, AA-LCR · Higher is better

Further details

Weights
Provider Benchmarks
Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)
Anthropic logoAnthropic
66
-
1M
$7.2
66
Not available
Anthropic
View
Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback)
Anthropic logoAnthropic
65
-
1M
$7.2
59
Not available
Anthropic
View
Claude Fable 5.1 (Adaptive Reasoning, High Effort, Default Fallback)
Anthropic logoAnthropic
62
-
1M
$7.2
49
Not available
Anthropic
View
Claude Fable 5.1 (Adaptive Reasoning, Medium Effort, Default Fallback)
Anthropic logoAnthropic
60
-
1M
$7.2
48
Not available
Anthropic
View
Claude Fable 5.1 (Adaptive Reasoning, Low Effort, Default Fallback)
Anthropic logoAnthropic
58
-
1M
$7.2
56
Not available
Anthropic
View
GPT-5.6 Luna (max)
OpenAI logoOpenAI
52
-
1M
$0.2
126
Not available
OpenAIAmazon Bedrock
View
GPT-5.6 Luna (xhigh)
OpenAI logoOpenAI
50
-
1M
$0.2
120
Not available
OpenAIMicrosoft Azure
View
GPT-5.6 Luna (high)
OpenAI logoOpenAI
47
-
1M
$0.2
115
Not available
OpenAIMicrosoft Azure
View
GPT-5.6 Luna (medium)
OpenAI logoOpenAI
39
-
1M
$0.2
110
Not available
OpenAI
View
GPT-5.6 Luna (low)
OpenAI logoOpenAI
34
-
1M
$0.2
109
Not available
OpenAI
View
GPT-5.6 Luna (Non-reasoning)
OpenAI logoOpenAI
27
-
1M
$0.2
112
Not available
OpenAIAmazon Bedrock
View