Claude Fable 5.1 (Low, Default Fallback) vs GPT-5.6 Luna (Medium)

Which is better for the money: Claude Fable 5.1 (Low, Default Fallback) by Anthropic or GPT-5.6 Luna (Medium) by OpenAI? Intelligence, total benchmark cost, and end-to-end time from Artificial Analysis & other sources, snapshot 2026-10-26.

Trade-off
AnthropicClaude Fable 5.1 (Low, Default Fallback)Off the frontier
Intelligence
46.80
Total cost
$3158
OpenAIGPT-5.6 Luna (Medium)Off the frontier
Intelligence
25.00
Total cost
$44.3
Verdict

Depends on your budget

Claude Fable 5.1 (Low, Default Fallback) scores 21.8 points higher (46.8 vs 25.0) but costs 71× as much to run the benchmark ($3158 vs $44.3; flagship vs budget cost classes). They are not alternatives at one budget: pick Claude Fable 5.1 (Low, Default Fallback) when you need intelligence above 25.0, and GPT-5.6 Luna (Medium) when 25.0 is enough.

MetricClaude Fable 5.1 (Low, Default Fallback)GPT-5.6 Luna (Medium)Difference
Intelligence (higher is better)46.825.0−46.6% GPT-5.6 Luna (Medium) is 46.6% less intelligent
Total AA cost (lower is better)$3,157.66$44.32−98.6% GPT-5.6 Luna (Medium) is 98.6% cheaper
End-to-end time (lower is better)11.25s6.64s−41.0% GPT-5.6 Luna (Medium) is 41.0% faster
Price per 1M tokens (in / out)$10.0 / $50.0$0.20 / $1.20
Input modalitiesText, ImageText, Image

GPT-5.6 Luna (Medium) vs Claude Fable 5.1 (Low, Default Fallback): 46.6% less intelligence, 98.6% less cost to run the AA benchmark, and 41.0% faster end-to-end.

Open this matchup in the interactive pickerClaude Fable 5.1 (Low, Default Fallback): what beats itGPT-5.6 Luna (Medium): what beats it
Today's Pareto frontier

Against the frontier

0204060$10$20$50$100$200$500$1k$2k$5k$10k$20kCost to run the Artificial Analysis Intelligence Index (USD, log scale)Intelligence IndexBeam 1.0 (Reflection): intelligence 30.30, $227Celeris-1 (Celeris): intelligence 6.30, $60.0Claude 4.5 Haiku (Reasoning) (Anthropic): intelligence 16.90, $547Claude 4.5 Sonnet (Reasoning) (Anthropic): intelligence 20.70, $1501Claude Fable 5 (Max, Opus 4.8 Fallback) (Anthropic): intelligence 49.60, $11161Claude Fable 5.1 (High, Default Fallback) (Anthropic): intelligence 51.20, $5242Claude Fable 5.1 (Max, Default Fallback) (Anthropic): intelligence 53.40, $13129Claude Fable 5.1 (Medium, Default Fallback) (Anthropic): intelligence 48.90, $3983Claude Fable 5.1 (Xhigh, Default Fallback) (Anthropic): intelligence 53.20, $9063Claude Haiku 5.5 (Low) (Anthropic): intelligence 29.50, $34.3Claude Haiku 5.5 (Max) (Anthropic): intelligence 43.40, $330Claude Opus 4.8 (Max) (Anthropic): intelligence 41.80, $6874Claude Opus 5 (High) (Anthropic): intelligence 48.10, $4332Claude Opus 5 (Low) (Anthropic): intelligence 39.40, $1561Claude Opus 5 (Max) (Anthropic): intelligence 50.80, $7275Claude Opus 5 (Medium) (Anthropic): intelligence 44.80, $2732Claude Opus 5 (Xhigh) (Anthropic): intelligence 49.70, $5868Claude Opus 5.5 (Low, Default Fallback) (Anthropic): intelligence 42.30, $860Claude Opus 5.5 (Medium, Default Fallback) (Anthropic): intelligence 51.20, $1627Claude Sonnet 4.6 (Max) (Anthropic): intelligence 30.10, $4925Claude Sonnet 5 (High) (Anthropic): intelligence 31.70, $2086Claude Sonnet 5 (Low) (Anthropic): intelligence 24.30, $653Claude Sonnet 5 (Max) (Anthropic): intelligence 38.20, $6998Claude Sonnet 5 (Medium) (Anthropic): intelligence 28.10, $1218Claude Sonnet 5 (Xhigh) (Anthropic): intelligence 34.40, $3255Claude Sonnet 5.5 (High, Default Fallback) (Anthropic): intelligence 46.80, $1027Claude Sonnet 5.5 (Low, Default Fallback) (Anthropic): intelligence 35.90, $482Claude Sonnet 5.5 (Max, Default Fallback) (Anthropic): intelligence 56.00, $7260Claude Sonnet 5.5 (Medium, Default Fallback) (Anthropic): intelligence 40.80, $622Claude Sonnet 5.5 (Xhigh, Default Fallback) (Anthropic): intelligence 51.90, $2177DeepSeek R1 (Jan '25) (DeepSeek): intelligence 11.40, $461DeepSeek V3 (Dec '24) (DeepSeek): intelligence 8.50, $25.4DeepSeek V3 0324 (DeepSeek): intelligence 9.70, $19.4DeepSeek V4 Flash 0420 (High) (DeepSeek): intelligence 24.40, $144DeepSeek V4 Flash 0420 (Max) (DeepSeek): intelligence 24.20, $159DeepSeek V4 Flash 0731 (Max) (DeepSeek): intelligence 34.30, $201DeepSeek V4 Flash Vision (Max) (DeepSeek): intelligence 34.80, $1081DeepSeek V4 Pro 0424 (Max) (DeepSeek): intelligence 30.40, $277DeepSeek V4 Pro 0813 (Max) (DeepSeek): intelligence 36.00, $1122DeepSeek V4 Pro 0813 (Non-reasoning) (DeepSeek): intelligence 20.40, $451DeepSeek V4.1 Flash (Max) (DeepSeek): intelligence 39.50, $526DeepSeek V4.1 Flash (Non-reasoning) (DeepSeek): intelligence 24.70, $194DeepSeek V4.1 Flash 1017 (Max) (DeepSeek): intelligence 45.10, $445Gemini 2.5 Pro (Google): intelligence 16.10, $804Gemini 3.1 Flash-Lite (Google): intelligence 15.60, $156Gemini 3.1 Pro Preview (Google): intelligence 29.70, $2072Gemini 3.5 Flash (High) (Google): intelligence 32.60, $3534Gemini 3.5 Flash-Lite (Google): intelligence 22.20, $337Gemini 3.6 Flash (High) (Google): intelligence 34.00, $1614Gemini 3.8 Flash (High) (Google): intelligence 40.90, $3770Gemma 4 E4B (Reasoning) (Google): intelligence 8.90, $14.7GLM-5.1 (Reasoning) (Z AI): intelligence 26.10, $1212GLM-5.2 (Max) (Z AI): intelligence 33.70, $1896GLM-5.3 (Low) (Z AI): intelligence 34.30, $1013GLM-5.3 (Max) (Z AI): intelligence 44.80, $2503GLM-5.3-Flash (Z AI): intelligence 41.80, $306GPT-5 mini (High) (OpenAI): intelligence 16.80, $189GPT-5.4 mini (Xhigh) (OpenAI): intelligence 24.10, $1349GPT-5.4 nano (Xhigh) (OpenAI): intelligence 20.70, $331GPT-5.5 (High) (OpenAI): intelligence 37.00, $3181GPT-5.5 (Medium) (OpenAI): intelligence 33.80, $1833GPT-5.5 (Xhigh) (OpenAI): intelligence 38.40, $4587GPT-5.5 Instant (June 2026) (OpenAI): intelligence 26.00, $987GPT-5.6 Luna (High) (OpenAI): intelligence 32.10, $108GPT-5.6 Luna (Low) (OpenAI): intelligence 21.00, $27.0GPT-5.6 Luna (Max) (OpenAI): intelligence 37.30, $320GPT-5.6 Luna (Non-reasoning) (OpenAI): intelligence 15.50, $23.0GPT-5.6 Luna (Xhigh) (OpenAI): intelligence 34.60, $179GPT-5.6 Sol (High) (OpenAI): intelligence 42.30, $1487GPT-5.6 Sol (Low) (OpenAI): intelligence 33.50, $637GPT-5.6 Sol (Max) (OpenAI): intelligence 47.00, $3465GPT-5.6 Sol (Medium) (OpenAI): intelligence 39.20, $997GPT-5.6 Sol (Xhigh) (OpenAI): intelligence 44.00, $2082GPT-5.6 Terra (High) (OpenAI): intelligence 34.20, $768GPT-5.6 Terra (Low) (OpenAI): intelligence 27.50, $350GPT-5.6 Terra (Max) (OpenAI): intelligence 42.10, $2501GPT-5.6 Terra (Medium) (OpenAI): intelligence 30.10, $447GPT-5.6 Terra (Non-reasoning) (OpenAI): intelligence 20.80, $256GPT-5.6 Terra (Xhigh) (OpenAI): intelligence 38.00, $1187GPT-6 Astra (High) (OpenAI): intelligence 50.90, $2925GPT-6 Astra (Low) (OpenAI): intelligence 45.80, $1537GPT-6 Astra (Max) (OpenAI): intelligence 52.70, $5324GPT-6 Astra (Medium) (OpenAI): intelligence 49.60, $2434GPT-6 Astra (Xhigh) (OpenAI): intelligence 52.40, $3803GPT-6 Luna (Non-reasoning) (OpenAI): intelligence 18.50, $19.2GPT-6 Sol (High) (OpenAI): intelligence 42.40, $605GPT-6 Sol (Low) (OpenAI): intelligence 34.20, $269GPT-6 Sol (Max) (OpenAI): intelligence 47.60, $1536GPT-6 Sol (Medium) (OpenAI): intelligence 39.80, $416GPT-6 Sol (Non-reasoning) (OpenAI): intelligence 28.50, $449GPT-6 Sol (Xhigh) (OpenAI): intelligence 44.20, $855GPT-6.1 Sol (Low) (OpenAI): intelligence 42.10, $250GPT-6.1 Terra (High) (OpenAI): intelligence 43.90, $239GPT-6.1 Terra (Low) (OpenAI): intelligence 36.20, $115GPT-6.1 Terra (Max) (OpenAI): intelligence 48.10, $909GPT-6.1 Terra (Non-reasoning) (OpenAI): intelligence 33.50, $154GPT-6.1 Terra (Xhigh) (OpenAI): intelligence 45.40, $365gpt-oss-120b (High) (OpenAI): intelligence 11.60, $123gpt-oss-20b (High) (OpenAI): intelligence 9.00, $28.8Granite 4.2 30B (IBM): intelligence 12.70, $111Granite 4.2 3B (IBM): intelligence 9.10, $14.9Granite 4.2 8B (IBM): intelligence 11.10, $53.1Grok 4.3 (High) (SpaceXAI): intelligence 24.90, $363Grok 4.3 (Non-reasoning) (SpaceXAI): intelligence 14.00, $216Grok 4.5 (High) (SpaceXAI): intelligence 38.80, $1120Grok 4.6 (High) (SpaceXAI): intelligence 44.30, $1963Grok 4.6 (Low) (SpaceXAI): intelligence 35.10, $614Grok 4.6 (Medium) (SpaceXAI): intelligence 42.80, $1557Grok 4.6 (Xhigh) (SpaceXAI): intelligence 44.20, $2242Grok 4.7 (High) (SpaceXAI): intelligence 46.30, $3473Grok 4.7 (Low) (SpaceXAI): intelligence 42.20, $1407Grok 4.7 (Xhigh) (SpaceXAI): intelligence 46.40, $4438Hy3 (Tencent): intelligence 25.30, $150Inkling (Xhigh) (Thinking Machines): intelligence 25.00, $1015Inkling Small (Thinking Machines): intelligence 25.70, $241Kimi K2.6 (Reasoning) (Kimi): intelligence 27.00, $1409Kimi K2.7 Code (Kimi): intelligence 25.80, $993Kimi K3 (Low) (Kimi): intelligence 30.10, $1190Kimi K3 (Max) (Kimi): intelligence 43.60, $3658Ling 3.0 Flash (InclusionAI): intelligence 20.10, $89.8Ling 3.1 Flash (InclusionAI): intelligence 41.10, $1015Ling 3.1 Flash 1019 (InclusionAI): intelligence 43.90, $1552Llama 4 Maverick (Meta): intelligence 9.30, $44.0Llama 4 Scout (Meta): intelligence 6.50, $73.6LongCat 2.0 (LongCat): intelligence 19.10, $545Mercury 2 (Inception): intelligence 10.80, $175Mercury 2.5 (Inception): intelligence 12.30, $189MiMo-V2.5 (Xiaomi): intelligence 21.80, $66.1MiMo-V2.5-Pro (Reasoning) (Xiaomi): intelligence 26.00, $240MiniMax-M2.7 (MiniMax): intelligence 22.80, $243MiniMax-M3 (MiniMax): intelligence 29.20, $538MiniMax-M3.1-Flash (MiniMax): intelligence 42.70, $283Ministral 3 14B (Mistral): intelligence 6.00, $37.6Ministral 3 3B (Mistral): intelligence 4.80, $12.2Ministral 3 8B (Mistral): intelligence 5.50, $27.5Mistral Large 3 (Mistral): intelligence 9.30, $46.4Mistral Large 4 Preview (Mistral): intelligence 38.40, $2003Mistral Medium 3.5 (Mistral): intelligence 14.20, $1147Mistral Small 3.1 (Mistral): intelligence 7.10, $27.8Mistral Small 3.2 (Mistral): intelligence 7.00, $122Mistral Small 4 (Reasoning) (Mistral): intelligence 11.30, $45.0Muse Glimmer (High) (Meta): intelligence 17.50, $146Muse Spark 1.1 (Xhigh) (Meta): intelligence 33.70, $1990Muse Spark 1.2 (Xhigh) (Meta): intelligence 39.60, $1715Muse Spark 1.3 (Max) (Meta): intelligence 48.10, $3905Muse Spark 1.3 (Xhigh) (Meta): intelligence 45.10, $2359Muse Spark Open (Xhigh) (Meta): intelligence 38.90, $1185Muse Wonder (Max) (Meta): intelligence 52.40, $9244Nemotron 3 Super 120B A12B (Reasoning) (NVIDIA): intelligence 12.80, $1319Nemotron 3 Ultra 550B A55B (Reasoning) (NVIDIA): intelligence 22.90, $596Nemotron 3.5 Lightning (NVIDIA): intelligence 12.90, $92.6Nemotron 3.5 Super VL (NVIDIA): intelligence 26.50, $283NVIDIA Nemotron 3 Nano 30B A3B (Reasoning) (NVIDIA): intelligence 8.90, $63.7o3-mini (High) (OpenAI): intelligence 11.00, $345Quasar 438B (Max, Based on GLM-5.2) (Multiverse Computing): intelligence 26.70, $246Qwen3 235B A22B 2507 (Reasoning) (Alibaba): intelligence 12.70, $234Qwen3 Coder Next (Alibaba): intelligence 9.20, $407Qwen3.5 122B A10B (Reasoning) (Alibaba): intelligence 15.60, $661Qwen3.5 397B A17B (Reasoning) (Alibaba): intelligence 18.40, $941Qwen3.5 9B (Reasoning) (Alibaba): intelligence 11.20, $329Qwen3.6 27B (Reasoning) (Alibaba): intelligence 21.40, $1145Qwen3.6 35B A3B (Reasoning) (Alibaba): intelligence 18.20, $896Qwen3.7 Max (Alibaba): intelligence 29.50, $1965Qwen3.7 Plus (Alibaba): intelligence 25.20, $428Qwen3.8 2.4T A95B (Alibaba): intelligence 39.90, $2632Qwen3.8 27B (Low) (Alibaba): intelligence 26.20, $1165Qwen3.8 27B (Medium) (Alibaba): intelligence 27.60, $1278Qwen3.8 27B (Non-reasoning) (Alibaba): intelligence 20.20, $2022Qwen3.8 27B (Xhigh) (Alibaba): intelligence 33.70, $1459Qwen3.8 Max (Alibaba): intelligence 40.20, $3172Qwen3.8 Max (0902) (Alibaba): intelligence 45.40, $4935Qwen3.8-Flash-Next (Alibaba): intelligence 39.80, $363Ring-2.6-1T (InclusionAI): intelligence 16.60, $576Solar Mini 4 (Upstage): intelligence 24.10, $659Solar Pro 3 (Upstage): intelligence 7.80, $131Solar Pro 4 (Upstage): intelligence 26.60, $737Step 5 Preview (StepFun): intelligence 43.70, $1190Trinity Large Thinking (Arcee AI): intelligence 10.80, $233GPT-6 Luna (Low) (OpenAI): intelligence 21.50, $10.6GPT-6 Luna (Medium) (OpenAI): intelligence 29.90, $31.2GPT-6 Luna (High) (OpenAI): intelligence 32.90, $47.9Claude Haiku 5.5 (Medium) (Anthropic): intelligence 34.50, $56.4GPT-6 Luna (Xhigh) (OpenAI): intelligence 34.60, $66.8Claude Haiku 5.5 (High) (Anthropic): intelligence 37.80, $94.1MiMo-V2.6-Flash (Xiaomi): intelligence 37.90, $110GPT-6 Luna (Max) (OpenAI): intelligence 38.10, $122Claude Haiku 5.5 (Xhigh) (Anthropic): intelligence 41.20, $158GPT-6.1 Terra (Medium) (OpenAI): intelligence 41.30, $175MiMo-V2.6-Pro (Xiaomi): intelligence 46.30, $207GPT-6.1 Sol (Medium) (OpenAI): intelligence 47.80, $361GPT-6.1 Sol (High) (OpenAI): intelligence 50.20, $521GPT-6.1 Sol (Xhigh) (OpenAI): intelligence 51.00, $662GPT-6.1 Sol (Max) (OpenAI): intelligence 51.80, $1082Gemini 4 Argon (High) (Google): intelligence 52.60, $2101Claude Opus 5.5 (High, Default Fallback) (Anthropic): intelligence 53.60, $2172Kimi K3.1 Pro (Kimi): intelligence 55.10, $3117Claude Opus 5.5 (Xhigh, Default Fallback) (Anthropic): intelligence 56.00, $4057Claude Opus 5.5 (Max, Default Fallback) (Anthropic): intelligence 57.60, $8708GPT-5.6 Luna (Medium) (OpenAI): intelligence 25.00, $44.3Claude Fable 5.1 (Low, Default Fallback) (Anthropic): intelligence 46.80, $3158Claude Fable 5.1 (Low, Default Fallback)GPT-5.6 Luna (Medium)GPT-6 Luna (Low)Claude Opus 5.5 (Max, Default Fallback)
Claude Fable 5.1 (Low, Default Fallback)GPT-5.6 Luna (Medium)Today's Pareto frontierEvery other model
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Agents: Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/claude-fable-5-1-low/gpt-5-6-luna-medium · Markdown: /api/v1/compare/claude-fable-5-1-low/gpt-5-6-luna-medium?format=md · llms.txt · agent skill