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GPT-5.5 is the hard-problem default; GPT-5.4 mini is the cost-sensitive workhorse. Learn when quality is worth the extra latency and tokens.
OpenAI's current GPT lineup is better thought of as a routing ladder. GPT-5.4 mini handles high-volume product work at lower cost; GPT-5.5 is the flagship for complex reasoning, coding, and professional workflows. Both can use the Responses API and reasoning effort controls, so the real decision is how much quality, latency, and cost the task deserves.
| Dimension | GPT-5.4 mini | GPT-5.5 |
|---|---|---|
| Role | High-volume workhorse | Flagship hard-problem solver |
| Latency | Faster | Fast, but heavier per call |
| Reasoning effort | Use none/low/medium first | Use medium/high/xhigh for hard tasks |
| Cost | $0.75 in / $4.50 out per M tokens | $5 in / $30 out per M tokens |
| Best at | RAG, agents, summarization, routine tool calls | complex code, research, multi-step planning |
from openai import OpenAI
client = OpenAI()
response = client.responses.create(
model="gpt-5.5",
reasoning={"effort": "high"},
input=task,
)
print(response.output_text)Use the Responses API and raise reasoning effort only when the task earns it.15 questions · take it digitally for instant feedback at tendril.neural-forge.io/learn/quiz/end-modelx-gpt5-turbo-vs-pro-builders
A developer is building a chatbot that answers thousands of customer questions per day. The questions are simple and follow predictable patterns. Which model would be most cost-effective for this use case?
A real-time stock trading application needs responses in under 200 milliseconds. Which model is more likely to meet this latency requirement?
A student is writing a research paper and needs answers with proper citations to academic sources. They also need the AI to handle complex arguments and multi-step logical reasoning. Which model should they choose?
In a production system handling mixed query types, what is the recommended approach for routing different requests to different models?
Which of these tasks is NOT listed as a best use case for GPT-5.4 mini?
If a company processes 10 million input tokens in a month using GPT-5.4 mini, what would be the approximate input cost?
A developer notices that GPT-5.4 mini keeps missing the same important edge case in their application. What does the lesson recommend doing?
What is 'tiered routing' in the context of AI model deployment?
A cheap classifier is added before making API calls to decide which model to use. What is the purpose of this component in a production system?
Which statement correctly describes the relationship between cost and quality for these two models?
What does the lesson identify as a key difference in latency between GPT-5.4 mini and GPT-5.5?
What is the input token cost for GPT-5.5 per million tokens?
For which of these scenarios would GPT-5.5 be the LEAST appropriate choice?
The lesson describes GPT-5.4 mini as ideal for RAG and agents. What characteristic makes it suitable for these applications?
What is meant by 'latency budget' as mentioned in the key terms?