| DeepSeek V4 | GPT-5.5 | |
|---|---|---|
| arenaElo | 1395 | 1432 |
| humanEval | 91 | 94.2 |
| sweBench | 62 | 66 |
| mmlu | 91.5 | 93 |
| gpqa | 73 | 68.7 |
| aime | 90 | 92 |
| Price in/out ($/M) | $1.74 / $3.48 | $12 / $48 |
GPT-5.5 ($12/$48 per M tokens) leads on Arena Elo, multimodal breadth (audio in/out) and creative writing. DeepSeek V4 ($1.74/$3.48) is roughly 85% cheaper for similar frontier-tier reasoning and offers full open-weights under MIT: no vendor lock-in. For consumer-facing voice products, GPT-5.5 wins; for batch document analysis or self-hosted enterprise, V4 is the rational choice.