SSyncDev

AI model comparison

Gemini 3.1 Pro Preview:Flex vs Grok 4 1 Fast Reasoning

Compare recorded price, context, output limits, speed, latency, capabilities, and input/output support. Every missing value stays visible, and unsourced benchmarks are excluded.

This Gemini 3.1 Pro Preview:Flex vs Grok 4 1 Fast Reasoning comparison is designed for teams choosing between two production model records, not for declaring a universal winner. Gemini 3.1 Pro Preview:Flex by Vertex via Requesty currently records 1.0M context, 65.5K maximum output, $1.00 input per 1M tokens, $6.00 output per 1M tokens. Grok 4 1 Fast Reasoning by Xai via Requesty records 2M context, 30K maximum output, $0.20 input per 1M tokens, $0.50 output per 1M tokens. The tables below separate documented capabilities, commercial limits, directory measurements, and source-linked benchmark evidence so you can see where the data is complete and where independent testing is still required.

Side-by-sideSpecs and pricing, compared

Vertex via Requesty

Gemini 3.1 Pro Preview:Flex

Gemini 3.1 Pro is the next iteration in the Gemini 3 series of models, a suite of highly capable, natively multimodal reasoning models. As of this model card’s date of publication, Gemini 3.1 Pro is Google’s most advanced model for complex tasks. Geminin 3.1 Pro can comprehend vast datasets and challenging problems from massively multimodal information sources, including text, audio, images, video, and entire code repositories.

Context
1.0M
Max output
65.5K
Input / 1M
$1.00
Output / 1M
$6.00
Output speed
—

Accepts

  • Text input
  • Image input

Produces

  • Text output
Full model profileVendor docs ↗
VS

Xai via Requesty

Grok 4 1 Fast Reasoning

A frontier multimodal model optimized specifically for high-performance agentic tool calling.

Context
2M
Max output
30K
Input / 1M
$0.20
Output / 1M
$0.50
Output speed
—

Accepts

  • Text input
  • Image input

Produces

  • Text output
Full model profileVendor docs ↗

At a glance

Decision snapshot

This is a directional summary of the values recorded in this directory—not a universal quality verdict. Test the finalists on your own prompts before committing.

Where Gemini 3.1 Pro Preview:Flex leads in recorded data

  • Maximum output: 65.5K

Where Grok 4 1 Fast Reasoning leads in recorded data

  • Context capacity: 2M
  • Input price: $0.20
  • Output price: $0.50

Context capacity

Higher listed limit

Gemini 3.1 Pro Preview:Flex:1.0M

Grok 4 1 Fast Reasoning:2M

Grok 4 1 Fast Reasoning

Maximum output

Higher listed limit

Gemini 3.1 Pro Preview:Flex:65.5K

Grok 4 1 Fast Reasoning:30K

Gemini 3.1 Pro Preview:Flex

Input price

Lower recorded price

Gemini 3.1 Pro Preview:Flex:$1.00

Grok 4 1 Fast Reasoning:$0.20

Grok 4 1 Fast Reasoning

Output price

Lower recorded price

Gemini 3.1 Pro Preview:Flex:$6.00

Grok 4 1 Fast Reasoning:$0.50

Grok 4 1 Fast Reasoning

Output speed

Higher recorded throughput

Gemini 3.1 Pro Preview:Flex:—

Grok 4 1 Fast Reasoning:—

No complete comparison

Time to first token

Lower recorded latency

Gemini 3.1 Pro Preview:Flex:—

Grok 4 1 Fast Reasoning:—

No complete comparison

Intelligence Index

Higher directory index

Gemini 3.1 Pro Preview:Flex:—

Grok 4 1 Fast Reasoning:—

No complete comparison

Evidence

Verified shared benchmarks

A score appears only when both records include a verified source. It is not treated as a universal ranking.

These two models haven't been measured on the same benchmark yet, so there's nothing meaningful to chart. Comparing scores from different tests would tell you more about the tests than the models — the specs and pricing above are the better guide here.

Specifications

Pricing, limits and capabilities

SpecificationGemini 3.1 Pro Preview:FlexGrok 4 1 Fast Reasoning
ProviderVertex via RequestyXai via Requesty
Model family——
Accepted inputstext, imagetext, image
Produced outputstexttext
Context window1.0M2MRecorded lead
Max output65.5KRecorded lead30K
Intelligence Index——
Input price / 1M$1.00$0.20Recorded lead
Output price / 1M$6.00$0.50Recorded lead
Output speed——
Time to first token——
Reasoning modeDocumentedDocumented
Tool callingDocumentedDocumented
Image inputDocumentedDocumented
Audio inputNot documentedNot documented
Structured outputDocumentedDocumented
LicenseNot documentedNot documented
ReleasedNot documentedNov 19, 2025

Workload guidance

Which model should you choose?

Gemini 3.1 Pro Preview:Flex currently leads on larger maximum output. Grok 4 1 Fast Reasoning currently leads on larger context, lower recorded input price, lower recorded output price. Choose according to the constraints that matter to your workload, then run the same representative prompts against both models before making a production commitment. Neither the larger number nor the lower price is automatically the better choice: prompt quality, tool reliability, modality support, rate limits, data policy, and provider implementation can change the result. Use this page to build a shortlist, confirm current terms in the linked sources, and validate quality, latency, and cost with your own traffic.

Provenance

Sources and data limits

Prices and hosted performance can change. SyncDev records source references and clearly separates documented specifications from measured values; confirm commercial terms with the provider before deployment.

Questions people ask

It compares recorded context and output limits, token prices, output speed, time to first token, Intelligence Index, modality support, tool and structured-output capabilities, release information, and only source-linked benchmarks verified on both records. Missing information is labeled rather than inferred.

Compare a different pair

Choose any two approved model records and review them with the same evidence rules.

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