Side-by-side technical and economic comparison between Google's Gemini 3.8 Flash and OpenAI's GPT-5.6 Mini.
| Metric | Gemini 3.8 Flash | GPT-5.6 Mini | Advantage |
|---|---|---|---|
| Provider Organization | OpenAI | — | |
| Standard Input / 1M | $0.75 | $0.30 | GPT-5.6 Mini (60% lower) |
| Cached Input / 1M | $0.075 | $0.03 | GPT-5.6 Mini lower |
| Output / 1M | $3.75 | $1.20 | GPT-5.6 Mini lower |
| Context Window | 1.05M | 400k | Gemini 3.8 Flash (1.05M) |
| Max Generation Tokens | 16.4k | 16.4k | Gemini 3.8 Flash |
| Tokenizer Family | Google Gemini SentencePiece (256k vocabulary) | OpenAI o200k_base (200k vocabulary) | — |
| Workload (per month) | Gemini 3.8 Flash | GPT-5.6 Mini |
|---|---|---|
| Chatbot10k requests · 500 in / 200 out | $11.25 | $3.90 |
| RAG app100k requests · 8,000 in / 1,200 out | $1,050.00 | $384.00 |
| Coding agent100k requests · 12,000 in / 2,000 out | $1,650.00 | $600.00 |
Standard rates, no caching or batch discounts. Model your own numbers below.
Opt for Gemini 3.8 Flash when your engineering requirements prioritize Google's ecosystem, specific tokenizer efficiencies (Calibrated Gemini Tokenizer (±4%)), or when your expected prompt-to-completion ratios favor its $0.75/M input rate.
Opt for GPT-5.6 Mini when looking for OpenAI's tooling integration, specific context window depth (400k tokens), or when output generation volume favors its $1.2/M rate.
At a typical 3:1 input-to-output token mix, GPT-5.6 Mini is about 65% cheaper than Gemini 3.8 Flash. Gemini 3.8 Flash costs $0.75 per 1M input and $3.75 per 1M output tokens; GPT-5.6 Mini costs $0.3 and $1.2.
Gemini 3.8 Flash has the larger context window: 1.05M tokens vs 400k.
Gemini 3.8 Flash: yes, cached input costs $0.075/1M. GPT-5.6 Mini: yes, cached input costs $0.03/1M.