Models · Compare
GPT-5.5 vs DeepSeek-V4 Pro
Rows highlighted in warm gray are where the models differ. Numbers carry their as-of date and primary source.
Specs
| Field | A: GPT-5.5 | B: DeepSeek-V4 Pro |
|---|---|---|
| Released | 2026-04-23 | — |
| Developer | OpenAI | DeepSeek |
| Openness | Proprietary | Open |
| License | Proprietary | MIT |
| OSI-approved | no | yes |
| Data released | no | no |
| Training code | no | no |
| Architecture | unknown | moe |
| Total params | — | 1.6T |
| Active params | — | 49B |
| Experts | — | — |
| Context window | 1.0M | 1.0M |
| Attention | unknown | hybrid-csa-hca |
| Position enc. | unknown | unknown |
| Pretraining tokens | — | 32.0T |
| Post-training | rlhf | sft, grpo, distillation |
| Training hardware | — | — |
| $/M input | $5.00 | $1.74 |
| $/M output | $30.00 | $3.48 |
| Output tok/sec | 66.7 | 29.8 |
Benchmarks
Missing scores render as not reported; never inferred. Bold highlights the leader per benchmark.
General reasoning
| MMLU-Pro | — | 87.5 2026-04-24 |
| GPQA-Diamond | 93.5 2026-05-21 | 88.8 2026-05-21 |
Code
| HumanEval | — | 76.8 2026-04-24 |
| SWE-Bench Verified | — | 80.6 2026-04-24 |
| LiveCodeBench | — | 93.5 2026-04-24 |
Context · A
Released April 23 2026, with GPT-5.5 and GPT-5.5 Pro hitting the API the next day. GPT-5.5 Instant replaced GPT-5.3 Instant as the ChatGPT default May 5 2026. Expanded context to 1M tokens; pricing above 272K input doubles input and 1.5x's output for the session.
Context · B
First V4-generation flagship, released April 24 2026 with a 1.6T-parameter MoE activating 49B per token. Combines Compressed Sparse Attention and Heavily Compressed Attention to cut single-token inference FLOPs to 27 percent of V3.2 and KV cache to 10 percent. 1M context is now the DeepSeek default. V4-Flash (284B / 13B active) shipped alongside.