OPENAI VS DEEPSEEK
GPT-5.5 Pro vs DeepSeek V4 Pro
DeepSeek V4 Pro is about 124x cheaper than GPT-5.5 Pro on a blended 3:1 input:output rate — the same 10K-in/2K-out request costs $0.0061 vs $0.66. GPT-5.5 Pro has the larger context window (1,047,576 vs 1,000,000 tokens).
Pricing verified
API pricing per 1M tokens
| Model | Input / 1M tokens | Output / 1M tokens | Blended (3:1 mix) |
|---|---|---|---|
| GPT-5.5 Pro | $30.00 | $180.00 | $67.50 |
| DeepSeek V4 Pro | $0.435 | $0.87 | $0.544 |
Rates from official OpenAI pricing and official DeepSeek pricing, checked 2026-08-11. Note: DeepSeek made its promotional rate the official list price after 2026-05-31.
What a real workload costs
Example: one request with 10,000 input tokens and 2,000 output tokens, then that request at 100,000 runs per month.
| Model | Per request (10K in / 2K out) | Per month (100K requests) | Monthly delta |
|---|---|---|---|
| GPT-5.5 Pro | $0.66 | $66,000 | +$65,391 |
| DeepSeek V4 Pro | $0.0061 | $609 | — |
Model your own prompt sizes and volumes in the token cost analyzer, or check caching savings with the prompt caching calculator.
Specs side by side
| Spec | GPT-5.5 Pro | DeepSeek V4 Pro |
|---|---|---|
| Provider | OpenAI | DeepSeek |
| Context window | 1,047,576 tokens | 1,000,000 tokens |
| Model class | Reasoning | Reasoning |
| Tokenizer | o200k_base (exact, public) | Proprietary (counts estimated) |
Count tokens for each model on its own page: GPT-5.5 Pro token counter and DeepSeek V4 Pro token counter. All OpenAI models are on the OpenAI Token Counter. All DeepSeek models are on the DeepSeek Token Counter.
FAQ
GPT-5.5 Pro vs DeepSeek V4 Pro FAQ
Which is cheaper, GPT-5.5 Pro or DeepSeek V4 Pro?
DeepSeek V4 Pro is cheaper. At rates checked 2026-08-11, GPT-5.5 Pro costs $30.00 input / $180.00 output per 1M tokens, while DeepSeek V4 Pro costs $0.435 input / $0.87 output — about a 124x difference on a typical 3:1 input-heavy workload.
How much does a real request cost on GPT-5.5 Pro vs DeepSeek V4 Pro?
A request with 10,000 input tokens and 2,000 output tokens costs about $0.66 on GPT-5.5 Pro and $0.0061 on DeepSeek V4 Pro. At 100,000 such requests per month that is $66,000 vs $609 — a difference of $65,391 per month.
Which has the bigger context window, GPT-5.5 Pro or DeepSeek V4 Pro?
GPT-5.5 Pro. It supports 1,047,576 tokens of context versus 1,000,000 tokens — roughly 786,000 English words in one request.
Do GPT-5.5 Pro and DeepSeek V4 Pro count tokens the same way?
Not exactly. GPT-5.5 Pro uses the published o200k_base tokenizer and DeepSeek V4 Pro uses a proprietary tokenizer (counts are estimates). The same prompt will tokenize differently, which shifts effective cost per word.