Compare
Gemini 3.8 Flash vs GPT-5.6 Luna: price, context and ranking
As of 18 October 2026, Gemini 3.8 Flash costs $0.825 per million input tokens and $4.125 per million output tokens; GPT-5.6 Luna costs $0.20 and $1.20.
- Blended price
- $1.65 / $0.45
per 1M tokens
Side by side
| Field | Gemini 3.8 Flash | GPT-5.6 Luna |
|---|---|---|
| Company | OpenAI | |
| Input price per 1M tokens | $0.825 | $0.20 |
| Output price per 1M tokens | $4.125 | $1.20 |
| Blended price per 1M tokens (3:1) | $1.65 | $0.45 |
| Context window | 1,048,576 | 1,050,000 |
| LMArena score | 1,498.9 | – |
| LMArena rank | 8 | – |
| Arena score per dollar | 908.4 | – |
| Usage share, 7 days | 1.1% | 1.0% |
| Providers | 7 | 7 |
| Added to OpenRouter | 2026-09-02 | 2026-07-09 |
Frequently asked questions
Which is cheaper, Gemini 3.8 Flash or GPT-5.6 Luna?
GPT-5.6 Luna is cheaper at a blended $0.45 per million tokens (three parts input to one part output), against $1.65 for Gemini 3.8 Flash.
Which has the longer context window, Gemini 3.8 Flash or GPT-5.6 Luna?
GPT-5.6 Luna has the longer context window, 1.05M tokens against 1.05M for Gemini 3.8 Flash.
Methodology and sources
The catalogue, prices, context lengths and provider counts come from OpenRouter's public Models API. They are fetched every day at 06:00 Istanbul time and stored as a daily snapshot. Weekly changes are calculated by Oesnada by comparing those snapshots; there is no data before 16 October 2026.
Usage shares are calculated from the daily token totals of OpenRouter's Data API: a model's tokens over the past 7 days divided by all tokens in the same period, including the aggregated long tail outside the top 50. Token counts come from each provider's own tokenizer and are not directly comparable across providers. The data is published by OpenRouter under CC BY 4.0. Variants such as ":free" are counted separately, so shares here can differ from OpenRouter's own ranking page.
Quality rankings come from LMArena's text (overall) leaderboard. A model is matched only when its name matches exactly; if a model has several listings, the highest-scoring one is used. "Frontier" means a model in the LMArena top 15.
"Best value" divides the LMArena score by the blended price (three parts input to one part output). Arena scores are not a linear scale, so the ratio is a rough guide. This page is produced automatically.
- OpenRouter Models API
- OpenRouter Rankings (Data API) (CC BY 4.0)
- LMArena leaderboard dataset (CC BY 4.0)
Related Oesnada stories
No related stories yet.
Download the data
Cite this page
Oesnada, "Gemini 3.8 Flash vs GPT-5.6 Luna: price, context and ranking", https://oesnada.com/ai-models/compare/google-gemini-3-8-flash-vs-openai-gpt-5-6-luna, accessed 18 October 2026.