Side-by-side technical and economic comparison between Anthropic's Claude Opus 5 and OpenAI's OpenAI o4-mini.
| Metric | Claude Opus 5 | OpenAI o4-mini | Advantage |
|---|---|---|---|
| Provider Organization | Anthropic | OpenAI | — |
| Standard Input / 1M | $5.00 | $1.10 | OpenAI o4-mini (78% lower) |
| Cached Input / 1M | $0.50 | $0.275 | OpenAI o4-mini lower |
| Output / 1M | $25.00 | $4.40 | OpenAI o4-mini lower |
| Context Window | 1M | 200k | Claude Opus 5 (1M) |
| Max Generation Tokens | 16.4k | 64k | OpenAI o4-mini |
| Tokenizer Family | Anthropic Claude BPE (~65k vocabulary) | OpenAI o200k_base (200k vocabulary) | — |
Opt for Claude Opus 5 when your engineering requirements prioritize Anthropic's ecosystem, specific tokenizer efficiencies (Calibrated Claude Tokenizer (±3%)), or when your expected prompt-to-completion ratios favor its $5/M input rate.
Opt for OpenAI o4-mini when looking for OpenAI's tooling integration, specific context window depth (200k tokens), or when output generation volume favors its $4.4/M rate.