GPTvsGemini

GPT 5.6 Luna vs Gemini 3.1 Pro Custom Tools

Side-by-side comparison of pricing, task quality, and projected cost at higher scale.

Pricing

Side-by-side pricing

GPT 5.6 Luna

Fast / Budget

Gemini 3.1 Pro Custom Tools

Mid-tier
Input $/MTok
$0.20
$2.00
Output $/MTok
$1.20
$12.00
Cache discount
90% off
90% off
Context
922K
1,048.576K

Quality

Task confidence comparison

Confidence score from zero to one hundred by task type, where higher is better.
Code Generation
70
vs
0
Code Review
68
vs
0
Summarization
84
vs
0
Q&A
85
vs
0
Extraction
89
vs
0
Reasoning
63
vs
0
Classification
91
vs
0
Creative Writing
58
vs
0
GPT 5.6 Luna
Gemini 3.1 Pro Custom Tools

Guidance

When to use GPT 5.6 Luna vs Gemini 3.1 Pro Custom Tools

Choose GPT 5.6 Luna when...

  • -Cost matters: 90% cheaper on input tokens

Choose Gemini 3.1 Pro Custom Tools when...

  • -You need a larger context window (1,048.576K vs 922K)
  • Similar performance; consider provider preference or ecosystem fit.

At scale

Cost at scale

Estimated cost assuming a seventy percent input and thirty percent output token split.
GPT 5.6 Luna
Gemini 3.1 Pro Custom Tools
100K tokens
$0.05Cheaper
$0.50
1M tokens
$0.82Cheaper
$8.20
10M tokens
$8.20Cheaper
$82.00

FAQ

When should I use GPT 5.6 Luna instead of Gemini 3.1 Pro Custom Tools?

GPT 5.6 Luna and Gemini 3.1 Pro Custom Tools perform similarly across all tracked tasks. Pick based on pricing and provider preference.

Is Gemini 3.1 Pro Custom Tools cheaper than GPT 5.6 Luna?

Gemini 3.1 Pro Custom Tools input costs $2.00/MTok, which is 900% more than GPT 5.6 Luna at $0.20/MTok.

What are the context window sizes for GPT 5.6 Luna and Gemini 3.1 Pro Custom Tools?

GPT 5.6 Luna has a 922K token context window. Gemini 3.1 Pro Custom Tools has a 1,048.576K token context window.

Track your real costs

Comparisons show estimated costs at list price. The dashboard reveals your real spend and savings.