DeepSeek V4 Pro vs GPT-5.5
DeepSeek V4 Pro and GPT-5.5 both shipped within 24 hours of each other in late April 2026 (V4 on April 24, GPT-5.5 on April 23). They both target the same problem: long-context reasoning at the frontier. GPT-5.5 leads benchmarks across the board, but DeepSeek V4 Pro costs $1.74 per million input tokens versus $5.00 for GPT-5.5, and ships under the MIT license with weights anyone can download. The choice comes down to closed-API quality versus open-source independence at roughly one-third the price.
Head-to-Head Specs
| Spec | DeepSeek V4 Pro | GPT-5.5 |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Input Price | $1.74/1M | $5.00/1M |
| Output Price | $3.48/1M | $30.00/1M |
| Context Window | 1M | 1M |
| Released | 2026-04 | 2026-04 |
| Capabilities | text, vision, code, reasoning | text, vision, tool-use, code, reasoning |
Benchmark Scores
| Benchmark | DeepSeek V4 Pro | GPT-5.5 | Winner |
|---|---|---|---|
| MMLU-Pro | 91.5 | 94.2 | GPT-5.5 |
| HumanEval | 94.8 | 97.1 | GPT-5.5 |
| GPQA Diamond | 73.1 | 78.3 | GPT-5.5 |
| MATH | 92.4 | 95.8 | GPT-5.5 |
| SWE-bench | 63.8 | 68.7 | GPT-5.5 |
See the full benchmark leaderboard for all models.
Category Breakdown
GPT-5.5 scores 94.2 vs DeepSeek V4 Pro at 91.5
GPT-5.5 at 97.1 vs V4 Pro at 94.8
GPT-5.5 at 68.7 vs V4 Pro at 63.8 on the TensorFeed harness
GPT-5.5 at 95.8 vs V4 Pro at 92.4
V4 Pro at $1.74/$3.48 vs GPT-5.5 at $5/$30 per 1M tokens
MIT license allows unrestricted self-hosting and fine-tuning
Both ship with native 1M token context windows
GPT-5.5 supports text, image, audio, and video; V4 Pro is text and vision
Choose DeepSeek V4 Pro when:
- ▸Self-hosted or on-premise deployments where weights matter
- ▸Fine-tuning for specialized domains
- ▸High-volume workloads where cost dominates
- ▸Teams that need full control over inference
Choose GPT-5.5 when:
- ▸Highest possible benchmark scores out of the box
- ▸Omnimodal applications (audio, video input)
- ▸Existing OpenAI ecosystem and tooling
- ▸Workloads where managed API beats self-hosting
Frequently Asked Questions
Which is better, DeepSeek V4 Pro or GPT-5.5?
It depends on your use case. DeepSeek V4 Pro from DeepSeek excels at self-hosted or on-premise deployments where weights matter, while GPT-5.5 from OpenAI is better for highest possible benchmark scores out of the box. See the full comparison above for detailed benchmarks and pricing.
How much does DeepSeek V4 Pro cost compared to GPT-5.5?
DeepSeek V4 Pro costs $1.74 input and $3.48 output per 1M tokens. GPT-5.5 costs $5.00 input and $30.00 output per 1M tokens.
What is the context window difference between DeepSeek V4 Pro and GPT-5.5?
DeepSeek V4 Pro supports 1M tokens, while GPT-5.5 supports 1M tokens.