Gemini 3.8 Flash vs GPT-6 Luna
Google's Gemini 3.8 Flash and OpenAI's GPT-6 Luna, compared on the figures Alevr runs on: list prices, context window, speed and intelligence grades, and the plan that includes each.
Gemini 3.8 Flash
Google's flagship multimodal Flash model with hybrid reasoning.
- Input / output per M
- $0.75 / $3.75
- Context
- 1.05M
- In Alevr from
- Lite
OpenAI
GPT-6 Luna
Fastest, most affordable GPT-6: summarization, extraction and quick answers with 1M context.
- Input / output per M
- $0.10 / $0.50
- Context
- 1.05M
- In Alevr from
- Free
Side by side.
| Gemini 3.8 Flash | GPT-6 Luna | |
|---|---|---|
| Lab | OpenAI | |
| Released | Sep 2026 | Sep 2026 |
| Context window | 1,048,576 tokens | 1,050,000 tokens |
| Input, per M tokens | $0.75 | $0.10 |
| Cached input, per M tokens | $0.08 | $0.01 |
| Output, per M tokens | $3.75 | $0.50 |
| Intelligence grade | 9 / 10Catalog estimate | 8 / 10Catalog estimate |
| Speed grade | 8 / 10Catalog estimate | 9 / 10Catalog estimate |
| Adjustable thinking | Yes | Yes |
| Reads images | Yes | Yes |
| Searches the web in Alevr | Yes | Yes |
| Drives agents and Code | Yes | Yes |
| Included in Alevr from | Lite€10.80 a month incl. VAT | Free€0 a month incl. VAT |
Which to pick.
Each answer below is a comparison of the figures above, nothing more. Costs use a chat turn of 800 input and 500 output tokens.
- For the lowest cost per messageGPT-6 Luna
- At list prices, 1,000 requests of a chat turn of 800 input and 500 output tokens cost $2.48 on Gemini 3.8 Flash and $0.33 on GPT-6 Luna. GPT-6 Luna is about 7.5× cheaper for this workload.
- For the hardest reasoningGemini 3.8 Flash
- Gemini 3.8 Flash has the higher intelligence grade, 9 against 8 out of 10. Neither model has an Artificial Analysis measurement in Alevr's latest benchmark sync yet, so both grades are the catalog's estimates and may move when one lands.
- For quick back-and-forthGPT-6 Luna
- GPT-6 Luna has the higher speed grade, 9 against 8 out of 10.
- For long documentsNo clear difference
- The context windows are close: 1.05M and 1.05M tokens.
- On a smaller Alevr planGPT-6 Luna
- GPT-6 Luna is included from Free (€0 a month incl. VAT); Gemini 3.8 Flash needs Lite (€10.80).
Pick Gemini 3.8 Flash
- for the hardest reasoning
Pick GPT-6 Luna
- for the lowest cost per message
- for quick back-and-forth
- for on a smaller Alevr plan
Use both in Alevr.
Alevr puts Claude, GPT, Gemini and 150+ models in one subscription, hosted in France. Plans start at €10.80 a month incl. VAT.
More comparisons
- Claude Sonnet 5.5 vs Gemini 3.8 Flash$2.00 / $10.00 vs $0.75 / $3.75 per M tokens
- Claude Opus 5.5 vs GPT-6.1 Sol$4.00 / $20.00 vs $2.00 / $10.00 per M tokens
- Claude Opus 5.5 vs GPT-6.1 Sol for coding$4.00 / $20.00 vs $2.00 / $10.00 per M tokens
- Claude Opus 5.5 vs GPT-6.1 Sol for writing$4.00 / $20.00 vs $2.00 / $10.00 per M tokens
- Claude Opus 5.5 vs GPT-6 Astra$4.00 / $20.00 vs $10.00 / $50.00 per M tokens
- Claude Fable 5.1 vs GPT-6 Astra$10.00 / $50.00 vs $10.00 / $50.00 per M tokens
Where these figures come from
Prices are each lab's API list price in US dollars per million tokens, as recorded in the model catalog Alevr bills from. Cached input is the rate a prompt-cache hit is billed at. Alevr subscribers do not pay per token: each plan includes a monthly usage budget.
Intelligence and speed are Alevr's 1 to 10 grades. Where Artificial Analysis has measured a model, the grade is computed from its Intelligence Index and median output speed. A model it has not measured yet carries an estimate from the lab's positioning, and the page says so. The benchmark sync last ran on 22 September 2026.
The figures change when labs change their prices. These pages are rebuilt from the same catalog each time Alevr ships, so they match what the app shows.
OpenRouter, a reseller, lists Gemini 3.8 Flash (google/gemini-3.8-flash) at $0.75 input and $3.75 output per million tokens. Resale rates can differ from the lab's own.