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Head-to-head comparison

Claude Fable 5.1 vs Gemma 4 31B

Claude Fable 5.1 (Anthropic) and Gemma 4 31B (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 9 September 2026

As of 9 September 2026, Claude Fable 5.1 holds the stronger ModelCap Index position (#3 vs #27); Gemma 4 31B is 147.1× cheaper per output token ($0.34/1M vs $50.00/1M); Claude Fable 5.1 offers the longer context window (1M vs 262K tokens); and Gemma 4 31B ships open weights.

Which should you choose?

Choose Claude Fable 5.1 if…

  • you want the stronger overall ModelCap Index position — #3 against #27 (87.7 vs 69.7 points).
  • you need the longer context window — 1M tokens against 262K.
  • Arena coding is your yardstick — 1517 against 1499.
  • AA Terminal-Bench 2.1 is your yardstick — 91.4% against 29.2%.
  • AA Humanity's Last Exam is your yardstick — 59.1% against 11.8%.
  • you want the more recently listed model — Claude Fable 5.1 was listed 1 September 2026, Gemma 4 31B 2 April 2026.

Choose Gemma 4 31B if…

  • API cost matters — $0.34/1M output tokens against $50.00/1M, about 147.1× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.09/1M against $10.00/1M.
  • you want to self-host: Gemma 4 31B ships open weights while Claude Fable 5.1 is api only.
  • you want provider choice — 13 listed API providers against 4.

Claude Fable 5.1 vs Gemma 4 31B: specs, pricing and context

Specification comparison of Claude Fable 5.1 and Gemma 4 31B
FieldClaude Fable 5.1AnthropicGemma 4 31BGoogle
ModelCap Index position#3#27
Index score87.769.7
EvidenceMeasuredMeasured
Input price / 1M tokens$10.00$0.09
Output price / 1M tokens$50.00$0.34
Context window1M tokens262K tokens
Max output tokens128K16K
API providers listed413
Weight accessAPI onlyOpen weights
Input modalitiesText, Image, FileImage, Text, Video
First listed1 September 20262 April 2026
PublisherAnthropicGoogle

Evidence: 5 public benchmark observations across 5 boards · 3 public benchmark observations across 3 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Claude Fable 5.1 vs Gemma 4 31B

Public benchmark boards where Claude Fable 5.1 or Gemma 4 31B has a published result
BoardClaude Fable 5.1Gemma 4 31BLeads
Arena codingArena (LMArena)15171491–1542Max14991484–1514Claude Fable 5.1
LMArena AgentLMArena14.5%12.6%–16.4%Max—Only one result
ARC-AGI-2ARC Prize Foundation90.0%Max—Only one result
AA Intelligence IndexArtificial Analysis53.4intelligence-index:v4.3:reasoning-unspecified—Only one result
AA Terminal-Bench 2.1Artificial Analysis91.4%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="Claude Fable 5.1 (max with fallback)":reasoning=true29.2%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="Gemma 4 31B (Non-reasoning)":reasoning=falseClaude Fable 5.1
AA τ²-Bench TelecomArtificial Analysis—65.5%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="Gemma 4 31B (Non-reasoning)":reasoning=falseOnly one result
AA Humanity's Last ExamArtificial Analysis59.1%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="Claude Fable 5.1 (max with fallback)":reasoning=true11.8%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="Gemma 4 31B (Non-reasoning)":reasoning=falseClaude Fable 5.1
Terminal-Bench 4.0Terminal-Bench (Laude Institute)57.9%54.1%–61.6%Claude Code · Max—Only one result
WildClawBench OpenClawWildClawBench—37.6Only one result

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 Gemma 4 31B: common questions

Is Claude Fable 5.1 better than Gemma 4 31B?

Claude Fable 5.1 ranks higher on the ModelCap Index as of 9 September 2026: #3 against #27. 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. Their published uncertainty intervals do not overlap, but the aggregate Index does not predict performance on every task; compare the relevant benchmark configurations before choosing.

Is Claude Fable 5.1 cheaper than Gemma 4 31B?

Gemma 4 31B is cheaper on output tokens: $0.34/1M against $50.00/1M. Input tokens are $10.00/1M for Claude Fable 5.1 and $0.09/1M for Gemma 4 31B. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens. For 1,000 requests with 2,000 input and 500 output tokens each (2M input + 0.5M output), the listed-rate estimate is $45.00 for Claude Fable 5.1 versus $0.35 for Gemma 4 31B. Gemma 4 31B costs 99.2% less in this scenario. This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the selected endpoint before budgeting.

Which has the bigger context window, Claude Fable 5.1 or Gemma 4 31B?

Claude Fable 5.1 has the larger context window: 1M tokens against 262K.

Which is better for coding, Claude Fable 5.1 or Gemma 4 31B?

Arena coding: Claude Fable 5.1 1517, Gemma 4 31B 1499 — Claude Fable 5.1 leads. AA Terminal-Bench 2.1: Claude Fable 5.1 91.4%, Gemma 4 31B 29.2% — Claude Fable 5.1 leads.

Are Claude Fable 5.1 and Gemma 4 31B open-weight models?

Claude Fable 5.1: API only. Gemma 4 31B: Open weights. 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 Gemma 4 31B?

ModelCap currently lists 4 API providers for Claude Fable 5.1 and 13 for Gemma 4 31B, 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 Gemma 4 31B comparison?

Every figure comes from the sealed ModelCap dataset published 9 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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