Gemini 3.1 Pro preview vs Grok 4

Gemini 3.1 Pro preview vs Grok 4: Gemini 3.1 Pro preview is cheaper by 33% on average. Gemini 3.1 Pro preview from Google Vertex AI (1,048,576-token context, reasoning, tool calls) vs. Grok 4 from xAI (256,000-token context, 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

0200,000

Requests / day5,000

01,000,000

Gemini 3.1 Pro previewCheaper

Google Vertex AI

$1,644/mo

Input $2.00/M · Output $12.00/M

Grok 4

xAI

$2,283/mo

Input $3.00/M · Output $15.00/M

At this workload, Gemini 3.1 Pro preview is 28% cheaper than Grok 4 — a savings of $639/month ($7,670/year).

Production recipe — Agent Command Center

strategy: cost-optimized
primary:
  model: gemini-3-1-pro-preview
  provider: vertex-ai
fallback:
  model: grok-4
  provider: xai
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	Grok 4 xAI
Input price	$2.00/M	$3.00/M
Output price	$12.00/M	$15.00/M
Context window	1,048,576	256,000
Max output	65,536	256,000
Function calling	✓	✓
Vision	✓	—
Audio input	✓	—
Reasoning	✓	—
Prompt caching	✓	✓
Structured output	✓	—
Pricing verified	May 12, 2026	May 12, 2026