AI models – When to use which model

Rule of thumb:

• Fast & inexpensive → Mini / Flash / Nano
• Standard & reliable → Large all-round models
• Complex & critical → Most powerful models
• EU / internal / data protection → Stackit models

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OpenAI

gpt-4o mini

• For: short questions, simple texts, quick answers
• When: everyday use, chat, summarizing, brainstorming
• Why: very fast and inexpensive, sufficient for ~80% of cases

gpt-4o

• For: standard all-round tasks
• When: when quality is more important than pure speed
• Why: strong in text comprehension, structure, and logic

gpt-4.1

• For: complex analyses, clear arguments
• When: strategy, concepts, in-depth explanations
• Why: more precise and stable than gpt-4o

gpt-4.1 mini

• For: better quality while maintaining high speed
• When: when gpt-4o mini is too superficial
• Why: good balance between quality and performance

gpt-5 mini

• For: demanding tasks with efficiency
• When: coding, structured outputs, longer texts
• Why: more modern and robust than the GPT-4 series

gpt-5 nano

• For: extremely simple, fast tasks
• When: auto-complete, short answers, mass tasks
• Why: extremely fast and inexpensive, but limited depth

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Google

Gemini 2.5 Flash

• For: maximum speed
• When: quick queries, brainstorming, iterations
• Why: very fast, good at overview and context

Gemini 2.5 Pro

• For: deep thinking and large contexts
• When: complex documents, comparisons, analyses
• Why: Google’s strongest model with high structural quality

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Perplexity AI

• For: looking things up, overview, fact checking, research
• When: questions with facts and sources
• Why? Answer with sources

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Quick decision-making aid

• “I just want a good answer” → gpt-4o
• “I need it fast” → gpt-4o mini or Gemini 2.5 Flash
• “It’s complicated or important” → gpt-4.1, gpt-5 mini, or Gemini 2.5 Pro
• “Search documents” → Gemini 2.5 Flash