Side-by-side technical and economic comparison between OpenAI's OpenAI o3 and Google's Gemini 2.5 Flash.
| Metric | OpenAI o3 | Gemini 2.5 Flash | Advantage |
|---|---|---|---|
| Provider Organization | OpenAI | — | |
| Standard Input / 1M | $2.00 | $0.30 | Gemini 2.5 Flash (85% lower) |
| Cached Input / 1M | $0.50 | $0.03 | Gemini 2.5 Flash lower |
| Output / 1M | $8.00 | $2.50 | Gemini 2.5 Flash lower |
| Context Window | 200k | 1.05M | Gemini 2.5 Flash (1.05M) |
| Max Generation Tokens | 100k | 8.2k | OpenAI o3 |
| Tokenizer Family | OpenAI o200k_base (200k vocabulary) | Google Gemma SentencePiece (~256k vocabulary) | — |
Opt for OpenAI o3 when your engineering requirements prioritize OpenAI's ecosystem, specific tokenizer efficiencies (Exact BPE (o200k_base)), or when your expected prompt-to-completion ratios favor its $2/M input rate.
Opt for Gemini 2.5 Flash when looking for Google's tooling integration, specific context window depth (1.05M tokens), or when output generation volume favors its $2.5/M rate.