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Head-to-head comparison

Gemini 3.1 Pro Preview vs GPT-5.5

Gemini 3.1 Pro Preview (Google) and GPT-5.5 (OpenAI) 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, GPT-5.5 holds the stronger ModelCap Index position (#13 vs #17); and Gemini 3.1 Pro Preview is 2.5× cheaper per output token ($12.00/1M vs $30.00/1M).

Which should you choose?

Choose Gemini 3.1 Pro Preview if…

  • API cost matters — $12.00/1M output tokens against $30.00/1M, about 2.5× cheaper.
  • your workload is prompt-heavy — input tokens cost $2.00/1M against $5.00/1M.
  • Arena coding is your yardstick — 1520 against 1520.
  • AA τ²-Bench Telecom is your yardstick — 95.6% against 93.9%.
  • AA Humanity's Last Exam is your yardstick — 47.0% against 45.8%.

Choose GPT-5.5 if…

  • you want the stronger overall ModelCap Index position — #13 against #17 (82.5 vs 81.5 points).
  • you want provider choice — 3 listed API providers against 2.
  • LMArena Agent is your yardstick — 5.0% against -5.8%.
  • AA Intelligence Index is your yardstick — 38.4 against 29.7.
  • you want the more recently listed model — GPT-5.5 was listed 24 April 2026, Gemini 3.1 Pro Preview 19 February 2026.

Gemini 3.1 Pro Preview vs GPT-5.5: specs, pricing and context

Specification comparison of Gemini 3.1 Pro Preview and GPT-5.5
FieldGemini 3.1 Pro PreviewGoogleGPT-5.5OpenAI
ModelCap Index position#17#13
Index score81.582.5
EvidenceMeasuredMeasured
Input price / 1M tokens$2.00$5.00
Output price / 1M tokens$12.00$30.00
Context window1M tokens1M tokens
Max output tokens66K128K
API providers listed23
Weight accessAPI onlyAPI only
Input modalitiesAudio, File, Image, Text, VideoFile, Image, Text
First listed19 February 202624 April 2026
PublisherGoogleOpenAI

Evidence: 4 public benchmark observations across 4 boards · 7 public benchmark observations across 7 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Gemini 3.1 Pro Preview vs GPT-5.5

Public benchmark boards where Gemini 3.1 Pro Preview or GPT-5.5 has a published result
BoardGemini 3.1 Pro PreviewGPT-5.5Leads
Arena codingArena (LMArena)15201515–152515201514–1526HighGemini 3.1 Pro Preview
LMArena AgentLMArena-5.8%-6.6%–-5.0%5.0%4.1%–6.0%X-HighGPT-5.5
ARC-AGI-2ARC Prize Foundation—85.0%X-HighOnly one result
ARC-AGI-3ARC Prize Foundation—0.4%HighOnly one result
AA Intelligence IndexArtificial Analysis29.7intelligence-index:v4.3:reasoning-unspecified38.4intelligence-index:v4.3:xhighGPT-5.5
AA τ²-Bench TelecomArtificial Analysis95.6%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="Gemini 3.1 Pro Preview":reasoning=true93.9%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="GPT-5.5 (xhigh)":reasoning=trueGemini 3.1 Pro Preview
AA Humanity's Last ExamArtificial Analysis47.0%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="Gemini 3.1 Pro Preview":reasoning=true45.8%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GPT-5.5 (xhigh)":reasoning=trueGemini 3.1 Pro Preview
Terminal-Bench 2.1 Terminus 2Terminal-Bench—78.0X-HighOnly one result
WildClawBench OpenClawWildClawBench—58.2Only 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.

Gemini 3.1 Pro Preview vs GPT-5.5: common questions

Is Gemini 3.1 Pro Preview better than GPT-5.5?

GPT-5.5 ranks higher on the ModelCap Index as of 22 September 2026: #13 against #17. 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 Gemini 3.1 Pro Preview cheaper than GPT-5.5?

Gemini 3.1 Pro Preview is cheaper on output tokens: $12.00/1M against $30.00/1M. Input tokens are $2.00/1M for Gemini 3.1 Pro Preview and $5.00/1M for GPT-5.5. 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 $10.00 for Gemini 3.1 Pro Preview versus $25.00 for GPT-5.5. Gemini 3.1 Pro Preview costs 60.0% 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, Gemini 3.1 Pro Preview or GPT-5.5?

Both publish a 1M-token context window.

Which is better for coding, Gemini 3.1 Pro Preview or GPT-5.5?

Arena coding: Gemini 3.1 Pro Preview 1520, GPT-5.5 1520 — Gemini 3.1 Pro Preview leads.

Are Gemini 3.1 Pro Preview and GPT-5.5 open-weight models?

Gemini 3.1 Pro Preview: API only. GPT-5.5: 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 Gemini 3.1 Pro Preview and GPT-5.5?

ModelCap currently lists 2 API providers for Gemini 3.1 Pro Preview and 3 for GPT-5.5, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Gemini 3.1 Pro Preview vs GPT-5.5 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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