Gemini 3.1 Pro preview vs GPT-5 nano

Gemini 3.1 Pro preview vs GPT-5 nano: GPT-5 nano is cheaper by 98% on average. Gemini 3.1 Pro preview from Google Vertex AI (1,048,576-token context, reasoning, tool calls) vs. GPT-5 nano 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.

3,000
01,048,576
400
0128,000
5,000
01,000,000
Google Vertex AI
$1,644/mo
Input $2.00/M · Output $12.00/M
GPT-5 nanoCheaper
Azure OpenAI
$47.18/mo
Input $0.0500/M · Output $0.400/M
At this workload, GPT-5 nano is 97% cheaper than Gemini 3.1 Pro preview — a savings of $1,596/month ($19,157/year).
Production recipe — Agent Command Center
strategy: cost-optimized
primary:
  model: gpt-5-nano
  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
Gemini 3.1 Pro preview GPT-5 nano
Input price $2.00/M $0.0500/M
Output price $12.00/M $0.400/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
Cheaper option
~98% cheaper than Gemini 3.1 Pro preview
Larger context
1,048,576 tokens
More capabilities
6 of 6 capability flags advertised

Benchmark comparison

Side-by-side public benchmark scores. Greener bar = winner.

Chatbot Arena ELOgeneral
Gemini 3.1 Pro preview
1,492
GPT-5 nano
1,325
GPQA Diamondreasoning
Gemini 3.1 Pro preview
94.3%
GPT-5 nano
HumanEvalcode
Gemini 3.1 Pro preview
GPT-5 nano
86.3%
SWE-bench Verifiedagent
Gemini 3.1 Pro preview
80.6%
GPT-5 nano
MMMU-Promultimodal
Gemini 3.1 Pro preview
80.5%
GPT-5 nano
ARC-AGI-2reasoning
Gemini 3.1 Pro preview
77.1%
GPT-5 nano
MMLU-Proreasoning
Gemini 3.1 Pro preview
GPT-5 nano
73.0%
SciCodecode
Gemini 3.1 Pro preview
59.0%
GPT-5 nano
Humanity's Last Examreasoning
Gemini 3.1 Pro preview
44.4%
GPT-5 nano