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Head-to-head comparison

Claude Opus 5.5 vs Gemma 4 31B

Claude Opus 5.5 (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 22 September 2026

As of 22 September 2026, Claude Opus 5.5 holds the stronger ModelCap Index position (#1 vs #29); Gemma 4 31B is 58.8× cheaper per output token ($0.34/1M vs $20.00/1M); Claude Opus 5.5 offers the longer context window (1M vs 262K tokens); and Gemma 4 31B ships open weights.

Which should you choose?

Choose Claude Opus 5.5 if…

  • you want the stronger overall ModelCap Index position — #1 against #29 (98.6 vs 73.8 points).
  • you need the longer context window — 1M tokens against 262K.
  • AA Humanity's Last Exam is your yardstick — 61.4% against 11.8%.
  • you want the more recently listed model — Claude Opus 5.5 was listed 22 September 2026, Gemma 4 31B 2 April 2026.

Choose Gemma 4 31B if…

  • API cost matters — $0.34/1M output tokens against $20.00/1M, about 58.8× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.09/1M against $4.00/1M.
  • you want to self-host: Gemma 4 31B ships open weights while Claude Opus 5.5 is api only.
  • you want provider choice — 11 listed API providers against 5.

Claude Opus 5.5 vs Gemma 4 31B: specs, pricing and context

Specification comparison of Claude Opus 5.5 and Gemma 4 31B
FieldClaude Opus 5.5AnthropicGemma 4 31BGoogle
ModelCap Index position#1#29
Index score98.673.8
EvidenceMeasuredMeasured
Input price / 1M tokens$4.00$0.09
Output price / 1M tokens$20.00$0.34
Context window1M tokens262K tokens
Max output tokens128K16K
API providers listed511
Weight accessAPI onlyOpen weights
Input modalitiesText, Image, FileImage, Text, Video
First listed22 September 20262 April 2026
PublisherAnthropicGoogle

Evidence: 2 public benchmark observations across 2 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 Opus 5.5 vs Gemma 4 31B

Public benchmark boards where Claude Opus 5.5 or Gemma 4 31B has a published result
BoardClaude Opus 5.5Gemma 4 31BLeads
Arena codingArena (LMArena)—14991483–1514Only one result
ARC-AGI-2ARC Prize Foundation93.3%High—Only one result
AA Intelligence IndexArtificial Analysis57.6intelligence-index:v4.3:reasoning-unspecified—Only one result
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 Analysis61.4%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="Claude Opus 5.5 (Adaptive Reasoning, Max Effort, Default Fallback)":reasoning=true11.8%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="Gemma 4 31B (Non-reasoning)":reasoning=falseClaude Opus 5.5
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 Opus 5.5 vs Gemma 4 31B: common questions

Is Claude Opus 5.5 better than Gemma 4 31B?

Claude Opus 5.5 ranks higher on the ModelCap Index as of 22 September 2026: #1 against #29. 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 overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.

Is Claude Opus 5.5 cheaper than Gemma 4 31B?

Gemma 4 31B is cheaper on output tokens: $0.34/1M against $20.00/1M. Input tokens are $4.00/1M for Claude Opus 5.5 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 $18.00 for Claude Opus 5.5 versus $0.35 for Gemma 4 31B. Gemma 4 31B costs 98.1% 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 Opus 5.5 or Gemma 4 31B?

Claude Opus 5.5 has the larger context window: 1M tokens against 262K.

Which is better for coding, Claude Opus 5.5 or Gemma 4 31B?

The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.

Are Claude Opus 5.5 and Gemma 4 31B open-weight models?

Claude Opus 5.5: 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 Opus 5.5 and Gemma 4 31B?

ModelCap currently lists 5 API providers for Claude Opus 5.5 and 11 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 Opus 5.5 vs Gemma 4 31B comparison?

Every figure comes from the sealed ModelCap dataset published 22 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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