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Claude Opus 5.5 vs Gemini 3.1 Pro

Claude Opus 5.5 leads the LLM Stats Score 59.7 to 43.2. Gemini 3.1 Pro is 1.8x cheaper per token.

Anthropic · Google · Updated for 2026

Which is better?

Claude Opus 5.5 leads the overall LLM Stats Score 59.7 to 43.2, ranking #1 overall.

In the 3 individual benchmarks reported for both models, Claude Opus 5.5 wins 3; this is a narrower head-to-head signal than the composite indexes.

On price, Gemini 3.1 Pro is roughly 1.8x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Claude Opus 5.5

  • overall performance matters — it scores 59.7 and ranks #1 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you value its reported benchmark strengths — it wins 3 of 3 exact shared results
  • you want the most recent training data — it shipped Sep 2026

Choose Gemini 3.1 Pro

  • cost matters — it's about 1.8x cheaper per token

At a glance

The differences that matter most.

Claude Opus 5.5
Anthropic
Gemini 3.1 Pro
Google
Core performance indexes
LLM Stats Score
59.7
#1
43.2
#45
Reasoning
57.8
#1
44.9
#33
Coding
51.7
#1
30.8
#49
Agents
44.5
#2
24.2
#56
Cost, coverage & limits
Benchmark wins
3 of 3
0 of 3
Input price
$4.00 / M
$2.00 / M
Output price
$20.00 / M
$12.00 / M
Context window
1,000,000
1,000,000

Capability indexes

Additional strengths measured across groups of related public benchmarks

3 shared
Index
Claude Opus 5.5
Gemini 3.1 Pro
Math
42.5#5
42.4#6
Vision
42.8#1
31.0#28
Tool use
32.9#2
22.8#41
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

31 reported for Claude Opus 5.5 · 20 for Gemini 3.1 Pro

3 shared

Claude Opus 5.5 outperforms in 3 benchmarks (DeepSWE 1.1, Legal Agent Benchmark, SWE-Bench Pro), while Gemini 3.1 Pro is better at 0 benchmarks.

Claude Opus 5.5 significantly outperforms across most benchmarks.

Wed Sep 23 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

Gemini 3.1 Pro costs less

For input processing, Claude Opus 5.5 ($4.00/1M tokens) is 2.0x more expensive than Gemini 3.1 Pro ($2.00/1M tokens).

For output processing, Claude Opus 5.5 ($20.00/1M tokens) is 1.7x more expensive than Gemini 3.1 Pro ($12.00/1M tokens).

In conclusion, Claude Opus 5.5 is more expensive than Gemini 3.1 Pro.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Wed Sep 23 2026 • llm-stats.com
Anthropic
Claude Opus 5.5
Input tokens$4.00
Output tokens$20.00
Best providerAnthropic
Google
Gemini 3.1 Pro
Input tokens$2.00
Output tokens$12.00
Best providerDeepinfra
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Both models have the same input context window of 1,000,000 tokens. Gemini 3.1 Pro can generate longer responses up to 1,000,000 tokens, while Claude Opus 5.5 is limited to 128,000 tokens.

Anthropic
Claude Opus 5.5
Input1,000,000 tokens
Output128,000 tokens
Google
Gemini 3.1 Pro
Input1,000,000 tokens
Output1,000,000 tokens
Wed Sep 23 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Claude Opus 5.5 and Gemini 3.1 Pro support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Opus 5.5

Text
Images
Audio
Video

Gemini 3.1 Pro

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Claude Opus 5.5

Proprietary

Closed source

Gemini 3.1 Pro

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Opus 5.5 was released on 2026-09-22, while Gemini 3.1 Pro was released on 2026-02-19.

Claude Opus 5.5 is 7 months newer than Gemini 3.1 Pro.

Claude Opus 5.5

Sep 22, 2026

0 days ago

7mo newer
Gemini 3.1 Pro

Feb 19, 2026

7 months ago

Knowledge Cutoff

When training data ends

Claude Opus 5.5 has a knowledge cutoff of 2026-06-01, while Gemini 3.1 Pro has a cutoff of 2025-01-31.

Claude Opus 5.5 has more recent training data (up to 2026-06-01), making it potentially better informed about events through that date compared to Gemini 3.1 Pro (2025-01-31).

Claude Opus 5.5

Jun 2026

1.4 yr newer
Gemini 3.1 Pro

Jan 2025

Provider Availability

Claude Opus 5.5 is available from Anthropic. Gemini 3.1 Pro is available from DeepInfra, Google.

Claude Opus 5.5

anthropic logo
Anthropic
Input Price:Input: $4.00/1MOutput Price:Output: $20.00/1M

Gemini 3.1 Pro

deepinfra logo
Deepinfra
Input Price:Input: $2.00/1MOutput Price:Output: $12.00/1M
google logo
Google
Input Price:Input: $2.50/1MOutput Price:Output: $15.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Claude Opus 5.5 and Gemini 3.1 Pro side-by-side, then vote on the output you prefer.

Claude Opus 5.5
✓ Preferred
Gemini 3.1 Pro
Open in Playground

FAQ

Common questions about Claude Opus 5.5 vs Gemini 3.1 Pro.

Which is better, Claude Opus 5.5 or Gemini 3.1 Pro?

Claude Opus 5.5 leads the LLM Stats Score 59.7 to 43.2. Claude Opus 5.5 is made by Anthropic and Gemini 3.1 Pro is made by Google. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Claude Opus 5.5 compare to Gemini 3.1 Pro in benchmarks?

Claude Opus 5.5 scores BenchCAD (with Python tool): 96.2%, Global-MMLU: 94.3%, SWE-bench Multilingual: 93.9%, MILU: 93.1%, ArXivMath: 91.2%. Gemini 3.1 Pro scores t2-bench: 99.3%, LiveCodeBench Pro: 96.2%, GPQA: 94.3%, MMMLU: 92.6%, BrowseComp: 85.9%.

Is Claude Opus 5.5 cheaper than Gemini 3.1 Pro?

Gemini 3.1 Pro is 2.0x cheaper for input tokens. Claude Opus 5.5 costs $4.00/M input and $20.00/M output via anthropic. Gemini 3.1 Pro costs $2.00/M input and $12.00/M output via deepinfra.

What are the context window sizes for Claude Opus 5.5 and Gemini 3.1 Pro?

Claude Opus 5.5 supports 1.0M tokens and Gemini 3.1 Pro supports 1.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Opus 5.5 and Gemini 3.1 Pro?

Key differences include LLM Stats Score (59.7 vs 43.2), input pricing ($4.00 vs $2.00/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Opus 5.5 and Gemini 3.1 Pro?

Claude Opus 5.5 is developed by Anthropic and Gemini 3.1 Pro is developed by Google.

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