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Head-to-head comparison

Claude Fable 5.1 vs Gemini 3.1 Pro Preview

Claude Fable 5.1 (Anthropic) and Gemini 3.1 Pro Preview (Google) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 3 September 2026

As of 3 September 2026, Claude Fable 5.1 holds the stronger ModelCap Index position (#2 vs #8); and Gemini 3.1 Pro Preview is 4.2× cheaper per output token ($12.00/1M vs $50.00/1M).

Which should you choose?

Choose Claude Fable 5.1 if…

  • you want the stronger overall ModelCap Index position — #2 against #8 (84.1 vs 78.5 points).
  • you want provider choice — 4 listed API providers against 2.
  • AA Intelligence Index is your yardstick — 65.7 against 47.7.
  • AA Terminal-Bench 2.1 is your yardstick — 91.4% against 73.8%.
  • AA Humanity's Last Exam is your yardstick — 59.1% against 47.0%.
  • you want the more recently listed model — Claude Fable 5.1 was listed 1 September 2026, Gemini 3.1 Pro Preview 19 February 2026.

Choose Gemini 3.1 Pro Preview if…

  • API cost matters — $12.00/1M output tokens against $50.00/1M, about 4.2× cheaper.
  • your workload is prompt-heavy — input tokens cost $2.00/1M against $10.00/1M.

Claude Fable 5.1 vs Gemini 3.1 Pro Preview: specs, pricing and context

Specification comparison of Claude Fable 5.1 and Gemini 3.1 Pro Preview
FieldClaude Fable 5.1AnthropicGemini 3.1 Pro PreviewGoogle
ModelCap Index position#2#8
Index score84.178.5
EvidenceMeasuredMeasured
Input price / 1M tokens$10.00$2.00
Output price / 1M tokens$50.00$12.00
Context window1M tokens1M tokens
Max output tokens128K66K
API providers listed42
Weight accessAPI onlyAPI only
Input modalitiesText, Image, FileAudio, File, Image, Text, Video
First listed1 September 202619 February 2026
PublisherAnthropicGoogle

Evidence: 2 public benchmark observations across 2 boards · 4 public benchmark observations across 4 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Claude Fable 5.1 vs Gemini 3.1 Pro Preview

Public benchmark boards where Claude Fable 5.1 or Gemini 3.1 Pro Preview has a published result
BoardClaude Fable 5.1Gemini 3.1 Pro PreviewLeads
Arena codingArena (LMArena)—15211516–1526Only one result
LMArena AgentLMArena—-3.1%-4.0%–-2.2%Only one result
ARC-AGI-2ARC Prize Foundation90.0%Max—Only one result
AA Intelligence IndexArtificial Analysis65.7intelligence-index47.7intelligence-indexClaude Fable 5.1
AA Terminal-Bench 2.1Artificial Analysis91.4%terminal-bench-2.173.8%terminal-bench-2.1Claude Fable 5.1
AA τ²-Bench TelecomArtificial Analysis—95.6%tau2-bench-telecomOnly one result
AA Humanity's Last ExamArtificial Analysis59.1%humanitys-last-exam47.0%humanitys-last-examClaude Fable 5.1

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

Claude Fable 5.1 vs Gemini 3.1 Pro Preview: common questions

Is Claude Fable 5.1 better than Gemini 3.1 Pro Preview?

Claude Fable 5.1 ranks higher on the ModelCap Index as of 3 September 2026: #2 against #8. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it.

Is Claude Fable 5.1 cheaper than Gemini 3.1 Pro Preview?

Gemini 3.1 Pro Preview is cheaper on output tokens: $12.00/1M against $50.00/1M. Input tokens are $10.00/1M for Claude Fable 5.1 and $2.00/1M for Gemini 3.1 Pro Preview. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens.

Which has the bigger context window, Claude Fable 5.1 or Gemini 3.1 Pro Preview?

Both publish a 1M-token context window.

Which is better for coding, Claude Fable 5.1 or Gemini 3.1 Pro Preview?

AA Terminal-Bench 2.1: Claude Fable 5.1 91.4%, Gemini 3.1 Pro Preview 73.8% — Claude Fable 5.1 leads.

Are Claude Fable 5.1 and Gemini 3.1 Pro Preview open-weight models?

Claude Fable 5.1: API only. Gemini 3.1 Pro Preview: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run Claude Fable 5.1 and Gemini 3.1 Pro Preview?

ModelCap currently lists 4 API providers for Claude Fable 5.1 and 2 for Gemini 3.1 Pro Preview, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Claude Fable 5.1 vs Gemini 3.1 Pro Preview comparison?

Every figure comes from the sealed ModelCap dataset published 3 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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