Gemini 3.1 Pro preview vs Gemini 3 Flash preview

Name: Gemini 3 Flash preview
Brand: Google Vertex AI
Price: 0.500000 USD

Gemini 3.1 Pro preview vs Gemini 3 Flash preview: Gemini 3 Flash preview is cheaper by 75% on average. Gemini 3.1 Pro preview from Google Vertex AI (1,048,576-token context, reasoning, tool calls) vs. Gemini 3 Flash preview from Google Vertex AI (1,048,576-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

065,536

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

Gemini 3 Flash previewCheaper

Google Vertex AI

$411/mo

Input $0.500/M · Output $3.00/M

At this workload, Gemini 3 Flash preview is 75% cheaper than Gemini 3.1 Pro preview — a savings of $1,233/month ($14,793/year).

Production recipe — Agent Command Center

strategy: cost-optimized
primary:
  model: gemini-3-flash-preview
  provider: vertex-ai
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	Gemini 3 Flash preview Google Vertex AI
Input price	$2.00/M	$0.500/M
Output price	$12.00/M	$3.00/M
Context window	1,048,576	1,048,576
Max output	65,536	65,535
Function calling	✓	✓
Vision	✓	✓
Audio input	✓	✓
Reasoning	✓	✓
Prompt caching	✓	✓
Structured output	✓	✓
Pricing verified	May 12, 2026	May 12, 2026