Model Comparison
Gemini 3 Pro vs GPT-5.6 LunaWhich is better in 2026?
GPT-5.6 Luna shows notably better performance in the majority of benchmarks. GPT-5.6 Luna is 2.0x cheaper per token.
Verdict: Gemini 3 Pro vs GPT-5.6 Luna — which is better?
Gemini 3 Pro (by Google) and GPT-5.6 Luna (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
Gemini 3 Pro outperforms in 1 benchmarks (MMMU-Pro), while GPT-5.6 Luna is better at 2 benchmarks (GPQA, MRCR v2 (8-needle)). GPT-5.6 Luna shows notably better performance in the majority of benchmarks.
On price, GPT-5.6 Luna is roughly 2.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.6 Luna also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose Gemini 3 Pro if…
- you want predictable pricing at $2.00/M input and $12.00/M output
Choose GPT-5.6 Luna if…
- you want the strongest raw capability — it leads on 2 of 3 shared benchmarks
- cost matters — it's about 2.0x cheaper per token
- you process long inputs — it offers a 1,050,000 token context window
- you want the most recent training data — it shipped Jul 2026
Performance Benchmarks
Comparative analysis across standard metrics
Gemini 3 Pro outperforms in 1 benchmarks (MMMU-Pro), while GPT-5.6 Luna is better at 2 benchmarks (GPQA, MRCR v2 (8-needle)).
GPT-5.6 Luna shows notably better performance in the majority of benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, Gemini 3 Pro ($2.00/1M tokens) is 2.0x more expensive than GPT-5.6 Luna ($1.00/1M tokens).
For output processing, Gemini 3 Pro ($12.00/1M tokens) is 2.0x more expensive than GPT-5.6 Luna ($6.00/1M tokens).
In conclusion, Gemini 3 Pro is more expensive than GPT-5.6 Luna.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-5.6 Luna accepts 1,050,000 input tokens compared to Gemini 3 Pro's 1,048,576 tokens. GPT-5.6 Luna can generate longer responses up to 128,000 tokens, while Gemini 3 Pro is limited to 65,536 tokens.
Input Capabilities
Supported data types and modalities
Both Gemini 3 Pro and GPT-5.6 Luna support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Gemini 3 Pro
GPT-5.6 Luna
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Gemini 3 Pro was released on 2025-11-18, while GPT-5.6 Luna was released on 2026-07-09.
GPT-5.6 Luna is 8 months newer than Gemini 3 Pro.
Nov 18, 2025
8 months ago
Jul 9, 2026
1 weeks ago
7mo newerKnowledge Cutoff
When training data ends
Gemini 3 Pro has a knowledge cutoff of 2025-01-31, while GPT-5.6 Luna has a cutoff of 2026-02-16.
GPT-5.6 Luna has more recent training data (up to 2026-02-16), making it potentially better informed about events through that date compared to Gemini 3 Pro (2025-01-31).
Jan 2025
Feb 2026
1.1 yr newerProvider Availability
Gemini 3 Pro is available from Google. GPT-5.6 Luna is available from OpenAI.
Gemini 3 Pro
GPT-5.6 Luna
Outputs Comparison
Key Takeaways
Gemini 3 Pro
View detailsGPT-5.6 Luna
View detailsOpenAI
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Gemini 3 Pro and GPT-5.6 Luna side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Gemini 3 Pro vs GPT-5.6 Luna.