Gemini 3.1 Pro preview vs GPT 5.1

Name: GPT 5.1
Brand: Azure OpenAI
Price: 1.250000 USD

Gemini 3.1 Pro preview vs GPT 5.1: GPT 5.1 is cheaper by 38% on average. Gemini 3.1 Pro preview from Google Vertex AI (1,048,576-token context, reasoning, tool calls) vs. GPT 5.1 from Azure OpenAI (272,000-token context, reasoning, tool calls). Use Agent Command Center to A/B both in shadow mode and pick the winner per workload.

Side-by-side cost

Live workload comparison

Same workload run through both models. The cheaper one is highlighted.

Input tokens / request3,000

01,048,576

Output tokens / request400

0128,000

Requests / day5,000

01,000,000

Gemini 3.1 Pro preview

Google Vertex AI

$1,644/mo

Input $2.00/M · Output $12.00/M

GPT 5.1Cheaper

Azure OpenAI

$1,179/mo

Input $1.25/M · Output $10.00/M

At this workload, GPT 5.1 is 28% cheaper than Gemini 3.1 Pro preview — a savings of $464/month ($5,570/year).

Production recipe — Agent Command Center

strategy: cost-optimized
primary:
  model: gpt-5-1
  provider: azure-openai
fallback:
  model: gemini-3-1-pro-preview
  provider: vertex-ai
shadow: { sample_rate: 0.05 }   # mirror 5% of traffic to compare quality live

Get started free →Routing docs ↗

	Gemini 3.1 Pro preview Google Vertex AI	GPT 5.1 Azure OpenAI
Input price	$2.00/M	$1.25/M
Output price	$12.00/M	$10.00/M
Context window	1,048,576	272,000
Max output	65,536	128,000
Function calling	✓	✓
Vision	✓	✓
Audio input	✓	—
Reasoning	✓	✓
Prompt caching	✓	✓
Structured output	✓	✓
Pricing verified	May 12, 2026	May 12, 2026