Gemini 3.1 Pro preview vs GPT-5 mini

Gemini 3.1 Pro preview vs GPT-5 mini: GPT-5 mini is cheaper by 88% on average. Gemini 3.1 Pro preview from Google Vertex AI (1,048,576-token context, reasoning, tool calls) vs. GPT-5 mini from 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 miniCheaper
OpenAI
$236/mo
Input $0.250/M · Output $2.00/M
At this workload, GPT-5 mini is 86% cheaper than Gemini 3.1 Pro preview — a savings of $1,408/month ($16,893/year).
Production recipe — Agent Command Center
strategy: cost-optimized
primary:
  model: gpt-5-mini
  provider: 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 mini
Input price $2.00/M $0.250/M
Output price $12.00/M $2.00/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
Cheaper option
~88% 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 mini
1,395
GPQA Diamondreasoning⚠ different settings
Gemini 3.1 Pro preview
94.3%
GPT-5 mini
78.4%
HumanEvalcode
Gemini 3.1 Pro preview
GPT-5 mini
93.5%
AIME 2024math
Gemini 3.1 Pro preview
GPT-5 mini
91.1%
MMLU-Proreasoning
Gemini 3.1 Pro preview
GPT-5 mini
82.0%
SWE-bench Verifiedagent⚠ different settings
Gemini 3.1 Pro preview
80.6%
GPT-5 mini
68.0%
MMMU-Promultimodal
Gemini 3.1 Pro preview
80.5%
GPT-5 mini
ARC-AGI-2reasoning
Gemini 3.1 Pro preview
77.1%
GPT-5 mini
SciCodecode
Gemini 3.1 Pro preview
59.0%
GPT-5 mini
Humanity's Last Examreasoning
Gemini 3.1 Pro preview
44.4%
GPT-5 mini