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Head-to-head comparison

Gemini 3.1 Pro Preview vs Grok 4.20 Multi-Agent

Gemini 3.1 Pro Preview (Google) and Grok 4.20 Multi-Agent (xAI) 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, Gemini 3.1 Pro Preview holds the stronger ModelCap Index position (#17 vs #18); Grok 4.20 Multi-Agent is 4.8× cheaper per output token ($2.50/1M vs $12.00/1M); and Grok 4.20 Multi-Agent offers the longer context window (2M vs 1M tokens).

Which should you choose?

Choose Gemini 3.1 Pro Preview if…

  • you want the stronger overall ModelCap Index position — #17 against #18 (81.5 vs 81.2 points).
  • you want provider choice — 2 listed API providers against 1.
  • Arena coding is your yardstick — 1520 against 1508.

Choose Grok 4.20 Multi-Agent if…

  • API cost matters — $2.50/1M output tokens against $12.00/1M, about 4.8× cheaper.
  • your workload is prompt-heavy — input tokens cost $1.25/1M against $2.00/1M.
  • you need the longer context window — 2M tokens against 1M.
  • you want the more recently listed model — Grok 4.20 Multi-Agent was listed 31 March 2026, Gemini 3.1 Pro Preview 19 February 2026.

Gemini 3.1 Pro Preview vs Grok 4.20 Multi-Agent: specs, pricing and context

Specification comparison of Gemini 3.1 Pro Preview and Grok 4.20 Multi-Agent
FieldGemini 3.1 Pro PreviewGoogleGrok 4.20 Multi-AgentxAI
ModelCap Index position#17#18
Index score81.581.2
EvidenceMeasuredMeasured
Input price / 1M tokens$2.00$1.25
Output price / 1M tokens$12.00$2.50
Context window1M tokens2M tokens
Max output tokens66K1.8M
API providers listed21
Weight accessAPI onlyAPI only
Input modalitiesAudio, File, Image, Text, VideoText, Image, File
First listed19 February 202631 March 2026
PublisherGooglexAI

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

Benchmark scores: Gemini 3.1 Pro Preview vs Grok 4.20 Multi-Agent

Public benchmark boards where Gemini 3.1 Pro Preview or Grok 4.20 Multi-Agent has a published result
BoardGemini 3.1 Pro PreviewGrok 4.20 Multi-AgentLeads
Arena codingArena (LMArena)15201515–152515081502–1514Beta · 0309Gemini 3.1 Pro Preview
LMArena AgentLMArena-5.8%-6.6%–-5.0%—Only one result
AA Intelligence IndexArtificial Analysis29.7intelligence-index:v4.3:reasoning-unspecified—Only one result
AA τ²-Bench TelecomArtificial Analysis95.6%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="Gemini 3.1 Pro Preview":reasoning=true—Only one result
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=true—Only 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 Grok 4.20 Multi-Agent: common questions

Is Gemini 3.1 Pro Preview better than Grok 4.20 Multi-Agent?

Gemini 3.1 Pro Preview ranks higher on the ModelCap Index as of 22 September 2026: #17 against #18. 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 Grok 4.20 Multi-Agent?

Grok 4.20 Multi-Agent is cheaper on output tokens: $2.50/1M against $12.00/1M. Input tokens are $2.00/1M for Gemini 3.1 Pro Preview and $1.25/1M for Grok 4.20 Multi-Agent. 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 $3.75 for Grok 4.20 Multi-Agent. Grok 4.20 Multi-Agent costs 62.5% 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 Grok 4.20 Multi-Agent?

Grok 4.20 Multi-Agent has the larger context window: 2M tokens against 1M.

Which is better for coding, Gemini 3.1 Pro Preview or Grok 4.20 Multi-Agent?

Arena coding: Gemini 3.1 Pro Preview 1520, Grok 4.20 Multi-Agent 1508 — Gemini 3.1 Pro Preview leads.

Are Gemini 3.1 Pro Preview and Grok 4.20 Multi-Agent open-weight models?

Gemini 3.1 Pro Preview: API only. Grok 4.20 Multi-Agent: 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 Grok 4.20 Multi-Agent?

ModelCap currently lists 2 API providers for Gemini 3.1 Pro Preview and 1 for Grok 4.20 Multi-Agent, 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 Grok 4.20 Multi-Agent 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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