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All comparisons · Prices checked 2026-10-01
GPT-6 Luna vs Gemini 3.8 Flash: API cost comparison
For a typical chatbot reply, GPT-6 Luna costs $0.0003 and Gemini 3.8 Flash costs $0.0025 per request: GPT-6 Luna is 7.1× cheaper. GPT-6 Luna is cheaper in every workload below.
API prices
| GPT-6 Luna | Gemini 3.8 Flash | |
|---|---|---|
| Maker | OpenAI | |
| Input / 1M tokens | $0.1 | $0.75 |
| Output / 1M tokens | $0.5 | $3.75 |
| Output vs input price | 5.0× | 5.0× |
| Context window | 922K tokens | 1.05M tokens |
| Tokens for the same English text | baseline (GPT o200k count) | ~95% of GPT's count (estimate) |
Cost by workload
| Workload (per 1,000 requests) | GPT-6 Luna | Gemini 3.8 Flash | Cheaper |
|---|---|---|---|
| Chatbot reply short question plus some chat history · 1,500 in / 400 out | $0.350 | $2.49 | GPT-6 Luna 7.1× cheaper |
| Document Q&A (RAG) retrieved passages plus a question · 8,000 in / 500 out | $1.05 | $7.48 | GPT-6 Luna 7.1× cheaper |
| Coding agent step large working context, short edit · 25,000 in / 800 out | $2.90 | $20.66 | GPT-6 Luna 7.1× cheaper |
| Summarize a long report long input, short summary · 20,000 in / 300 out | $2.15 | $15.32 | GPT-6 Luna 7.1× cheaper |
| Write an article short brief, long draft · 800 in / 2,000 out | $1.08 | $7.69 | GPT-6 Luna 7.1× cheaper |
GPT-6 Luna is cheaper on both input and output, so it costs less for every kind of request. The gap is 7.1× on input and 7.1× on output once the tokenizer difference is included.
Same text, different token counts. Each company uses its own tokenizer. By our estimate GPT-6 Luna counts about 5% more tokens than Gemini 3.8 Flash for the same English text, and the costs above already include that. Paste your own prompt into the token counter to see both counts.
Monthly cost
| Monthly volume | GPT-6 Luna | Gemini 3.8 Flash |
|---|---|---|
| 10,000 chatbot replies / month | $3.50 | $24.94 |
| 100,000 chatbot replies / month | $35.00 | $249 |
| 1,000,000 chatbot replies / month | $350 | $2,494 |
Calculate your own
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Token counts are for English text measured with GPT's tokenizer; each model's own tokenizer difference is applied automatically.
Questions
Which is cheaper, GPT-6 Luna or Gemini 3.8 Flash?
For a typical chatbot reply (1,500 input and 400 output tokens), GPT-6 Luna costs $0.0003 and Gemini 3.8 Flash costs $0.0025 per request, so GPT-6 Luna is 7.1× cheaper. GPT-6 Luna is cheaper in every workload below.
How much do GPT-6 Luna and Gemini 3.8 Flash cost per million tokens?
GPT-6 Luna costs $0.1 per 1M input tokens and $0.5 per 1M output tokens. Gemini 3.8 Flash costs $0.75 input and $3.75 output. Prices checked 2026-10-01.
Do both models count the same text as the same number of tokens?
No. Each model family has its own tokenizer, so the same text can be a different number of tokens. The costs on this page already include that difference (estimated from GPT's tokenizer).
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Paste a real prompt to see its exact tokens and cost on GPT-6 Luna, Gemini 3.8 Flash and 30+ other models.
Open the token counter →Standard API list prices, short-context tier, no caching or batch discounts. Prices change; check each provider's pricing page before large jobs.