Model comparison
DeepSeek V4 Pro vs GPT 5.5
DeepSeek V4 Pro (DeepSeek) and GPT 5.5 (OpenAI) side by side: what each costs per million tokens through Rapid Router, how much context each takes, what each supports, and where independent benchmarks place them. Same API, same key; switching is a one-string change.
| DeepSeek V4 Pro | GPT 5.5 | |
|---|---|---|
| Input price per 1M | $1.30 | $5.00 |
| Output price per 1M | $2.60 | $30.00 |
| Context window | 1M tokens | 1.1M tokens |
| Max output | 393K tokens | 128K tokens |
| Input types | text | text, image, pdf |
| Capabilities | tools, JSON, reasoning | tools, JSON, vision, reasoning |
| Author | DeepSeek | OpenAI |
| LMArena Overall | 1451 | 1471 |
| LMArena Coding | 1469 | 1494 |
| LMArena Math | 1454 | 1487 |
| LMArena Creative writing | 1446 | 1455 |
| LMArena Instruction following | 1448 | 1479 |
| LMArena Hard prompts | 1461 | 1489 |
| LMArena Vision | — | 1297 |
| LMArena Web dev | 1582 | — |
| GPQA Diamond | 90.9% | 90.7% |
| SWE-bench Verified | 77.6% | — |
| OTIS Mock AIME | 96.7% | 84.4% |
| SimpleQA Verified | 47.0% | 63.0% |
Scores from LMArena and Epoch AI, as published; a blank cell means not measured there.
What a month costs on each
| Workload | DeepSeek V4 Pro | GPT 5.5 |
|---|---|---|
| Chatbot month (15M in, 4M out) | $29.90 | $195.00 |
| RAG month (40M in, 3M out) | $59.80 | $290.00 |
| Coding month (60M in, 10M out) | $104.00 | $600.00 |
On a typical 75/25 input-output mix, DeepSeek V4 Pro costs less (about 86% less than GPT 5.5). GPT 5.5 takes the longer prompt at 1.1M tokens. Try your own numbers in the cost calculator.
Call either one
curl https://rapidrouter.ai/api/v1/chat/completions \
-H "Authorization: Bearer $RAPIDROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model": "deepseek/deepseek-v4-pro", "messages": [{"role": "user", "content": "Hello"}]}'
# the other one: change the model string
-d '{"model": "openai/gpt-5.5", ...}'Common questions
Which is cheaper, DeepSeek V4 Pro or GPT 5.5?
DeepSeek V4 Pro is cheaper on a typical mix of 75% input and 25% output tokens, by about 86%. Through Rapid Router both are billed at the provider list price per million tokens.
Which has the larger context window?
GPT 5.5, at 1.1M tokens. DeepSeek V4 Pro offers 1M tokens.
Can I switch between DeepSeek V4 Pro and GPT 5.5 without changing code?
Yes. Both are callable at https://rapidrouter.ai/api/v1 with the same OpenAI-compatible request; only the model string changes (deepseek/deepseek-v4-pro or openai/gpt-5.5).
How do I pay for DeepSeek V4 Pro or GPT 5.5?
Top up a Rapid Router balance by card in US dollars, and both models debit that balance per request.
More DeepSeek models: DeepSeek API pricing · More GPT: OpenAI API pricing