GPT-4o Mini vs Claude Haiku 4.5: Cost & Quality Comparison 2026
Head-to-head comparison of the two most popular small LLM APIs — pricing, performance, caching advantages, and which to choose for your use case.
GPT-4o Mini and Claude Haiku 4.5 are the two most popular small models for high-volume, cost-sensitive applications. Both are significantly cheaper than their flagship counterparts — but they have different strengths. This guide compares cost, performance, and when to choose each.
Pricing Comparison
Cost at Scale: 10M Requests/Month
Typical chatbot request: 500 input tokens, 300 output tokens:
GPT-4o Mini vs Claude Haiku: Strengths
GPT-4o Mini Wins At
Claude Haiku 4.5 Wins At
The Caching Tiebreaker
If your application has a large, consistent system prompt (500+ tokens), Claude Haiku's prompt caching changes the math entirely. With a 1,000-token system prompt cached at 90% hit rate:
With caching, Haiku's effective input cost drops dramatically — making it even cheaper than GPT-4o Mini for prompt-heavy applications.
Verdict
Choose GPT-4o Mini for: structured output / function calling, vision, OpenAI/Azure ecosystem lock-in, or if you need the Realtime API.
Choose Claude Haiku 4.5 for: chatbots with large system prompts (prompt caching), instruction-heavy workflows, safety-critical applications, or if you want to avoid cloud lock-in.
Consider Gemini 2.5 Flash as a third option — 1M context, aggressive pricing, and competitive quality. Often the best value when context length matters.
Compare directly: GPT-4o Mini vs Claude Haiku → | Chatbot cost calculator →