All tasks / Comparisons

Claude Fable 5.1 vs Gemini 3.8 Flash

Compared only on public benchmark results, across the 10 tasks where both are listed: Claude Fable 5.1 is a tier higher in 3 of 10 shared tasks, Gemini 3.8 Flash in 1, they share a tier in 4.

Claude Fable 5.1

Anthropic's highest-priced Claude tier, positioned for demanding reasoning and long-horizon agentic work.

Vendor: Anthropic
Weights: Closed: API and apps only
Released: 1 Sep 2026
API price: $10 in / $50 out per 1M tokens
License: proprietary
Last verified: 18 Oct 2026

Alternatives to Claude Fable 5.1

Gemini 3.8 Flash

Google's Flash tier of faster, lower-cost Gemini models, aimed at agents, coding and high-volume use.

Vendor: Google
Weights: Closed: API and apps only
Released: 2 Sep 2026
API price: $0.75 in / $3.75 out per 1M tokens
License: proprietary
Last verified: 18 Oct 2026

Alternatives to Gemini 3.8 Flash

Task by task

Task	Claude Fable 5.1	Gemini 3.8 Flash	Higher tier
Chat & assistants Models	S1,502 on LMArena Text Arena (overall, style control) · Cloud	S1,496 on LMArena Text Arena (overall, style control) · Cloud	Same tier
Search & research Models	S1,233 on LMArena Search Arena (style control) · Cloud	–No public result yet · Cloud	Claude Fable 5.1
Writing Models	S1,485 on LMArena Text Arena: Creative Writing (style control) · Cloud	S1,487 on LMArena Text Arena: Creative Writing (style control) · Cloud	Same tier
Documents & OCR Models	–No public result yet · Cloud	–No public result yet · Cloud	—
Coding Models	A1,742 on LMArena WebDev / Code Arena (overall) · Cloud	C1,586 on LMArena WebDev / Code Arena (overall) · Cloud	Claude Fable 5.1
Image understanding Models	S1,286 on LMArena Vision Arena (overall, style control) · Cloud	S1,289 on LMArena Vision Arena (overall, style control) · Cloud	Same tier
Vector graphics & logos Models	C1,300 on Design Arena SVG · Cloud	C1,294 on Design Arena SVG · Cloud	Same tier
Browser & computer agents Models	–No public result yet · Cloud	–No public result yet · Cloud	—
Workflow automation Models	C59.4% on AutomationBench-AA (Artificial Analysis) · Cloud	B59.9% on AutomationBench-AA (Artificial Analysis) · Cloud	Gemini 3.8 Flash
Slides & presentations Models	S1,328 on Design Arena Python-PPTX Slides · Cloud	B1,179 on Design Arena Python-PPTX Slides · Cloud	Claude Fable 5.1

A tier spans a range of scores, and small gaps on a leaderboard are often within its margin of error, so only a different tier counts as ahead. How we rank.

Same benchmark, both results

Benchmark	Claude Fable 5.1	Gemini 3.8 Flash	Snapshot
Artificial Analysis Intelligence Index Composite index over Artificial Analysis' own evaluation suite, higher is better	53 Claude Fable 5.1 (Max, Default Fallback)	41 Gemini 3.8 Flash (High)	18 Oct 2026
AutomationBench-AA (Artificial Analysis) Score: average share of each task's objectives completed across 657 business-workflow tasks in 40 simulated SaaS apps via REST APIs; a task with any guardrail (business-rule) violation scores zero, higher is better	59.4% Claude Fable 5.1 (Max, Default Fallback)	59.9% Gemini 3.8 Flash (High)	19 Oct 2026
Design Arena Python-PPTX Slides Elo rating from crowdsourced blind pairwise votes on PowerPoint decks that models build with python-pptx in Design Arena's agent harness, higher is better	1,328 Claude Fable 5.1	1,179 Gemini 3.8 Flash	18 Oct 2026
Design Arena SVG Elo rating from crowdsourced blind pairwise votes on SVG markup that models generate from a prompt (icons, illustrations, diagrams, artistic compositions), higher is better	1,300 Claude Fable 5.1	1,294 Gemini 3.8 Flash	19 Oct 2026
EQ-Bench Creative Writing v3 Elo score from LLM-judged pairwise comparisons of creative-writing outputs (rubric score shown alongside), higher is better	2,162 claude-fable-5-1	1,748 gemini-3.8-flash	24 Sep 2026
LMArena Text Arena (overall, style control) Arena score (Bradley-Terry rating from pairwise human votes, style-controlled default view), higher is better	1,502 Claude Fable 5.1 (Max)	1,496 Gemini 3.8 Flash (High)	15 Oct 2026
LMArena Text Arena: Creative Writing (style control) Arena score (Bradley-Terry rating from pairwise human votes, creative-writing prompts only, style-controlled view), higher is better	1,485 Claude Fable 5.1 (Max)	1,487 Gemini 3.8 Flash (High)	15 Oct 2026
LMArena Vision Arena (overall, style control) Arena score (Bradley-Terry rating from pairwise human votes on image + text prompts, style-controlled view), higher is better	1,286 claude-fable-5.1-max	1,289 gemini-3.8-flash-high	9 Oct 2026
LMArena WebDev / Code Arena (overall) Arena score (Bradley-Terry rating from pairwise human votes on web-app generation), higher is better	1,742 Claude Fable 5.1 (Max)	1,586 Gemini 3.8 Flash (High)	18 Oct 2026
ParseBench (models) Overall: mean of five rule-based dimension scores (tables, charts, content faithfulness, semantic formatting, visual grounding) on ~2,000 human-verified enterprise pages, higher is better	78.9% Anthropic Fable 5.1	72.1% Google Gemini 3.8 Flash (Thinking High)	9 Oct 2026
SWE-Bench Pro V2 (public set, full) Resolve rate on 642 validated long-horizon tasks from 11 copyleft repositories, re-graded on a pristine image under a locked offline protocol, higher is better	99.1% Fable 5.1 (Claude Code) high	94.9% Gemini 3.8 Flash (mini-swe-agent) high	19 Oct 2026