GPT-5-mini vs Claude Haiku 4.5
A budget model showdown between OpenAI GPT-5-mini and Anthropic Claude Haiku 4.5. Covers pricing, context windows, speed, limitations, and which cheap AI model to pick for cost-sensitive production applications.
Specs Comparison
| Feature | GPT-5-mini (OpenAI) | Claude Haiku 4.5 (Anthropic) |
|---|---|---|
| Provider | OpenAI | Anthropic |
| Context Window | 128K tokens | 200K tokens |
| Max Output | 16K tokens | 8K tokens |
| Input Pricing | $0.40 / 1M tokens | $0.80 / 1M tokens |
| Output Pricing | $1.60 / 1M tokens | $4.00 / 1M tokens |
| Multimodal | Text, Images | Text, Images |
| Speed (TTFT) | ~200ms | ~250ms |
| Function Calling | Yes | Yes (Tool Use) |
| Web Search | Yes (Responses API) | No |
| Streaming | Yes | Yes |
| Temperature Control | No (not supported) | Yes (0.0 - 1.0) |
| API Style | Conversations + Responses API | Messages API |
GPT-5-mini (OpenAI)
Pros
- Cheapest OpenAI model for production applications
- Built-in web search via Responses API
- Conversations API provides automatic context persistence
- Good all-around performance for chat, classification, and summarization
- Very low latency with fast time-to-first-token
- Strong function-calling reliability inherited from GPT-5 family
Cons
- Does not support the temperature parameter (returns 400 error)
- Less reliable for creative or varied output due to no temperature control
- Smaller context window than Haiku (128K vs 200K)
- Can produce more generic responses without temperature tuning
- Newer model with less community testing and documentation
Best for
Cost-sensitive applications using OpenAI ecosystem features (web search, Conversations API, function calling) where temperature control is not needed.
Claude Haiku 4.5 (Anthropic)
Pros
- Full temperature control for creative and varied outputs
- Larger context window (200K tokens vs 128K)
- Excellent instruction following — does exactly what you ask
- Strong safety alignment reduces harmful or off-topic outputs
- Reliable and well-tested in production applications
- Better at nuanced, multi-step instructions
Cons
- More expensive than GPT-5-mini (roughly 2x input, 2.5x output)
- No built-in web search capability
- No conversation persistence API (must manage context yourself)
- Smaller max output (8K vs 16K tokens)
- No audio input support
Best for
Applications requiring precise instruction following, temperature-controlled output, and tasks where response quality matters more than cost. Best for content generation, analysis, and structured data extraction.
Verdict
For production apps that need temperature control (creative writing, varied responses, content generation), use gpt-4.1-mini instead of GPT-5-mini, or use Claude Haiku 4.5 for its excellent instruction following. For apps using OpenAI ecosystem features (web search, Conversations API), GPT-5-mini is cheaper but lacks temperature support. Haiku 4.5 offers the best quality-to-price ratio for tasks requiring precise, controllable outputs.
Frequently Asked Questions
Why can I not use temperature with GPT-5-mini?
GPT-5-mini does not support the temperature parameter and returns a 400 error if you include it. This is a known limitation. If your application needs temperature control, use gpt-4.1-mini (OpenAI) or Claude Haiku 4.5 (Anthropic) instead.
Which budget model is cheaper, GPT-5-mini or Claude Haiku 4.5?
GPT-5-mini is cheaper. It costs $0.40/$1.60 per million input/output tokens, while Haiku 4.5 costs $0.80/$4.00. GPT-5-mini is about 2x cheaper on input and 2.5x cheaper on output. However, the price difference is small in absolute terms for most applications.
Which budget AI model is better for chat applications?
GPT-5-mini is better for chat apps that use OpenAI features like Conversations API (automatic context management) and web search. Claude Haiku 4.5 is better for chat apps that need precise instruction following and temperature-controlled personality. Both perform well for general chat.
Should I use gpt-4.1-mini instead of GPT-5-mini?
If your app relies on the temperature parameter for varied or creative outputs, yes — use gpt-4.1-mini. It is still a current OpenAI model, supports temperature, and works reliably with the Responses API. Only switch to GPT-5-mini if you do not need temperature control.
Need help choosing?
AI 4U Labs builds with both GPT-5-mini and Claude Haiku 4.5. We'll recommend the right tool for your specific use case and build it for you in 2-4 weeks.
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