GPT-6 Luna Pro vs Gemini 3.5 Flash: price, context window and capabilities
GPT-6 Luna Pro (openai/gpt-6-luna-pro) from OpenAI and Gemini 3.5 Flash (google/gemini-3.5-flash) from Google are both multimodal language models on the OceanToken API. GPT-6 Luna Pro costs less per token than Gemini 3.5 Flash: $0.10 against $1.35 per 1M input tokens (93% less) and $0.50 against $8.10 per 1M output tokens (94% less). Gemini 3.5 Flash is 10% off its official price on OceanToken, for every account. Their context windows are almost the same size, about 1.05M tokens: GPT-6 Luna Pro takes 1,050,000 tokens and Gemini 3.5 Flash 1,048,576. Both support tool calling, reasoning, structured outputs, image input and file input; only Gemini 3.5 Flash also lists audio input and video input.
Side by side
| Spec | GPT-6 Luna Pro | Gemini 3.5 Flash −10% |
|---|---|---|
| Model | GPT-6 Luna Proopenai/ | Gemini 3.5 Flashgoogle/ |
| Publisher | OpenAI | |
| Kind | Text & vision | Text, vision, audio & video |
| Context window | 1.05M tokens1,050,000 | 1.05M tokens1,048,576 |
| Input price | $0.10 / 1M tokens | $1.35 / 1M tokens |
| Output price | $0.50 / 1M tokens | $8.10 / 1M tokens |
| Cached input price | $0.01 / 1M tokens | $0.15 / 1M tokens |
| Cache write price | $0.125 / 1M tokens | $1.583 / 1M tokens |
| Web search price | $0.01 / search | $0.014 / search |
| Discount (vs official, top tier) | — | −10% |
| Inputs | text, images and files | text, images, files, audio and video |
| Outputs | text | text |
| Tool calling | Yes | Yes |
| Reasoning | Yes | Yes |
| Structured outputs | Yes | Yes |
About these prices
Which should you choose?
- Choose GPT-6 Luna Pro to spend less per token: 93% less for input and 94% less for output than Gemini 3.5 Flash.
- Context size does not separate them: both hold about 1.05M tokens.
- Choose Gemini 3.5 Flash if you need audio input and video input: GPT-6 Luna Pro does not list them.
- Not sure? Call both with the same OceanToken API key and compare them on your own prompts; each request is billed per use from one prepaid balance.
Get API Key GPT-6 Luna Pro Gemini 3.5 Flash
Frequently asked questions
Which is cheaper, GPT-6 Luna Pro or Gemini 3.5 Flash?
GPT-6 Luna Pro. GPT-6 Luna Pro costs less per token than Gemini 3.5 Flash: $0.10 against $1.35 per 1M input tokens (93% less) and $0.50 against $8.10 per 1M output tokens (94% less). Gemini 3.5 Flash is 10% off its official price on OceanToken, for every account. The OceanToken console always shows the current price.
Which has the larger context window, GPT-6 Luna Pro or Gemini 3.5 Flash?
GPT-6 Luna Pro, by 1,424 tokens. Their context windows are almost the same size, about 1.05M tokens: GPT-6 Luna Pro takes 1,050,000 tokens and Gemini 3.5 Flash 1,048,576.
Can I call both GPT-6 Luna Pro and Gemini 3.5 Flash with one API key?
Yes. Both are on the OceanToken API at https://api.oceantoken.ai/v1: one API key and one prepaid balance call either model. Send the model id openai/gpt-6-luna-pro or google/gemini-3.5-flash.
Models and publishers
GPT-6 Luna Pro · Gemini 3.5 Flash · All OpenAI models · All Google models
More comparisons
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