Head-to-head · Google vs OpenAI
Gemini 3.1 Pro vs GPT-6 Luna
Quick answer: Gemini 3.1 Pro stands out for strong multimodal coverage. GPT-6 Luna stands out for extremely cheap for bulk processing. Reviewed September 2026.
Overview
Gemini 3.1 Pro: Gemini 3.1 Pro, released by Google in February 2026, is a multimodal model with strong agentic capabilities. It is listed at $2 and $12 per million tokens for prompts up to 200,000 tokens ($4 and $18 above that) and is offered in preview on the Gemini API.
GPT-6 Luna: GPT-6 Luna, launched on 22 September 2026, is the small, low-cost member of the GPT-6 family at $0.10 and $0.50 per million tokens. It targets high-volume tasks where cost and speed matter most.
At a glance
| Dimension | Gemini 3.1 Pro | GPT-6 Luna |
|---|---|---|
| Vendor | OpenAI | |
| Starting price | API: $2 in / $12 out per M tokens | API: $0.10 in / $0.50 out per M tokens |
| Pricing model | Paid | Paid |
| Free tier | No | No |
| Category | Generative AI | Generative AI |
Strengths and limits
Gemini 3.1 Pro
- Strong multimodal coverage
- Deep Google ecosystem integration
- Competitive price for a Pro-tier model
Watch out for
- Listed as a preview model on the pricing page
- Google has said Gemini 4 is coming
- Output style can vary between interfaces
GPT-6 Luna
- Extremely cheap for bulk processing
- Fast responses
- Good fit for classification and extraction
Watch out for
- Not suited to the hardest reasoning tasks
- Newest release with limited track record
- Quality varies by task, so test on your own data
Key features
Gemini 3.1 Pro
- Multimodal understanding across text, images, audio and video
- Agentic and tool-use capabilities
- Tiered pricing for prompts over 200,000 tokens
- Available through the Gemini API and Google Cloud
GPT-6 Luna
- Very low per-token pricing
- Built for high-volume and latency-sensitive work
- Shares GPT-6 family technology
- Available through the OpenAI API
Pricing compared
Gemini 3.1 Pro is priced by usage rather than by seat: API: $2 in / $12 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing.
GPT-6 Luna is priced by usage rather than by seat: API: $0.10 in / $0.50 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing.
Frequently asked questions
Which is better, Gemini 3.1 Pro or GPT-6 Luna?
It depends on the work. Gemini 3.1 Pro stands out for strong multimodal coverage. GPT-6 Luna stands out for extremely cheap for bulk processing.
How do Gemini 3.1 Pro and GPT-6 Luna compare on price?
Gemini 3.1 Pro is priced by usage rather than by seat: API: $2 in / $12 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing. GPT-6 Luna is priced by usage rather than by seat: API: $0.10 in / $0.50 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing.
Is there a free option between Gemini 3.1 Pro and GPT-6 Luna?
Neither lists a permanent free tier. Look for trials or usage-based pricing to test on real work first.