Comparison · DeepSeek and OpenAI
DeepSeek V4 Pro 0813 vs GPT-5.4
Listed API prices of DeepSeek V4 Pro 0813 and GPT-5.4 turned into the cost of the same three standard tasks and what each provider’s API documentation says about features that break on a switch. Output quality, speed and answer length are not compared.
Calculated impact cost per task and per month
For an L2 task (deep analysis over a 50,000-token document, 3 steps), DeepSeek V4 Pro 0813 costs $0.222 and GPT-5.4 $0.443 at the prices listed in the United States on , so DeepSeek V4 Pro 0813 is 49.9 % less than GPT-5.4, counting visible output only, without cache discounts or hidden reasoning.
| Task | DeepSeek V4 Pro 0813, per task | GPT-5.4, per task | DeepSeek V4 Pro 0813, per month | GPT-5.4, per month | DeepSeek V4 Pro 0813 vs GPT-5.4, per task |
|---|---|---|---|---|---|
| L1Micro-task (classification or strict JSON extraction) | $0.0028per L1 task | $0.0067per L1 task | $40.47per month | $98.55per month | −58.9 % |
| L2Deep analysis over a 50,000-token document | $0.222per L2 task | $0.443per L2 task | $3,237.70per month | $6,460.50per month | −49.9 % |
| L3Agentic coding loop, 15 steps | $1.77per L3 task | $3.42per L3 task | $25,872.66per month | $49,986.75per month | −48.2 % |
Calculated Per month: 20 tasks an hour around the clock, 730 hours.
Prices USD per 1M tokens
| Price | DeepSeek V4 Pro 0813 | GPT-5.4 |
|---|---|---|
| Input, per 1M tokens | $1.32 | $2.50 |
| Output, per 1M tokens | $3.96 | $15.00 |
| Price from | Provider's price list · source page Published | OpenRouter · source page (data) Published |
| Read | · the United States | · the United States |
| Context window | 1,048,576 tokens | 1,050,000 tokens |
What can I use it for? six common tasks, our data checks
Quality on your task: not measured by Measured Lab yet.
| Task | DeepSeek V4 Pro 0813 | GPT-5.4 |
|---|---|---|
| Answer customer messages | Fits on price and context | — |
| Pull data from invoices and documents with strict JSON and page images | Not confirmed: reads text only, per the OpenRouter listing; strict JSON output partly, per DeepSeek’s documentation | — |
| Summarize documents and meetings | Fits on price and context | — |
| Translate content | Fits on price and context | — |
| Chat assistant on your website | Fits on price and context | — |
| Write and review code with tool calls | Fits on price and context | — |
| Tasks it fits | 5 of 6 | — |
Checks of our data for six common tasks: a published price, a context window and answer length for the task and, where the task needs them, strict JSON output, page images and tool calls; prices, cost a month and terms for each model on its model card. GPT-5.4 is not in the model picker. Compare models for your own task in the model picker.
What breaks when you switch Published provider documentation
Moving from DeepSeek to OpenAI: every feature that DeepSeek’s documentation lists as supported is also listed as supported by OpenAI.
Moving from OpenAI to DeepSeek, 4 of the 5 features may not carry over, by each provider’s documentation:
- Strict JSON schemas — OpenAI: yes; DeepSeek: partly. Code that parses answers without checks starts failing where a provider promises only valid JSON, not your schema.
- Parallel tool calls — OpenAI: yes; DeepSeek: not stated. An agent built around several calls per turn gets one call per turn: more round trips, more input tokens, slower runs.
- Streamed tool arguments — OpenAI: yes; DeepSeek: not stated. An interface that shows arguments as they are written sees nothing until the whole call is ready.
- Cache covers tool definitions — OpenAI: yes; DeepSeek: not stated. Where the cache does not cover tool definitions, a long tool list is paid as fresh input on every request.
| Feature of the API | DeepSeek | OpenAI |
|---|---|---|
| Strict JSON schemas | Partly | Yes |
| Parallel tool calls | Not stated | Yes |
| Streamed tool arguments | Not stated | Yes |
| Reasoning with tools | Yes | Yes |
| Cache covers tool definitions | Not stated | Yes |
What each provider’s own API documentation says, read ; “not stated” is not the same as “no”. Quotes and sources: what breaks when you switch AI APIs.