GPT-5.4 Mini vs Phi-4 Mini Flash Reasoning
GPT-5.4 Mini (2026) and Phi-4 Mini Flash Reasoning (2025) are frontier-tier reasoning models from OpenAI and Microsoft Research. GPT-5.4 Mini ships a 400K-token context window, while Phi-4 Mini Flash Reasoning ships a 128K-token context window. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing. The goal is to make the tradeoff clear before deeper testing.
GPT-5.4 Mini is safer overall; choose Phi-4 Mini Flash Reasoning when provider fit matters.
Decision scorecard
Local evidence first| Signal | GPT-5.4 Mini | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Long context |
| Context window | 400K | 128K |
| Cheapest output | $4.5/1M tokens | - |
| Provider routes | 2 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- GPT-5.4 Mini has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.4 Mini has broader tracked provider coverage for fallback and procurement flexibility.
- GPT-5.4 Mini uniquely exposes Multimodal, Function calling, and Tool use in local model data.
- Local decision data tags GPT-5.4 Mini for Coding, RAG, and Agents.
- Local decision data tags Phi-4 Mini Flash Reasoning for Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
GPT-5.4 Mini
$1,725
Cheapest tracked route: OpenAI API
Phi-4 Mini Flash Reasoning
Unavailable
No complete token price in local provider data
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for GPT-5.4 Mini and Phi-4 Mini Flash Reasoning; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Multimodal, Function calling, and Tool use before moving production traffic.
- No overlapping tracked provider route is sourced for Phi-4 Mini Flash Reasoning and GPT-5.4 Mini; plan for SDK, billing, or endpoint changes.
- GPT-5.4 Mini adds Multimodal, Function calling, and Tool use in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-03-05 | 2025-12-01 |
| Context window | 400K | 128K |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | 1 |
| Knowledge cutoff | 2025-08 | - |
Pricing and availability
| Pricing attribute | GPT-5.4 Mini | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Input price | $0.75/1M tokens | - |
| Output price | $4.5/1M tokens | - |
| Providers |
Capabilities
| Capability | GPT-5.4 Mini | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Vision | No | No |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on multimodal input: GPT-5.4 Mini, function calling: GPT-5.4 Mini, tool use: GPT-5.4 Mini, structured outputs: GPT-5.4 Mini, and code execution: GPT-5.4 Mini. Both models share reasoning mode, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
Pricing coverage is uneven: GPT-5.4 Mini has $0.75/1M input tokens and Phi-4 Mini Flash Reasoning has no token price sourced yet. Provider availability is 2 tracked routes versus 1. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose GPT-5.4 Mini when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose Phi-4 Mini Flash Reasoning when provider fit are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, GPT-5.4 Mini or Phi-4 Mini Flash Reasoning?
GPT-5.4 Mini supports 400K tokens, while Phi-4 Mini Flash Reasoning supports 128K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is GPT-5.4 Mini or Phi-4 Mini Flash Reasoning open source?
GPT-5.4 Mini is listed under Proprietary. Phi-4 Mini Flash Reasoning is listed under 1. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for multimodal input, GPT-5.4 Mini or Phi-4 Mini Flash Reasoning?
GPT-5.4 Mini has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for reasoning mode, GPT-5.4 Mini or Phi-4 Mini Flash Reasoning?
Both GPT-5.4 Mini and Phi-4 Mini Flash Reasoning expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for function calling, GPT-5.4 Mini or Phi-4 Mini Flash Reasoning?
GPT-5.4 Mini has the clearer documented function calling signal in this comparison. If function calling is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run GPT-5.4 Mini and Phi-4 Mini Flash Reasoning?
GPT-5.4 Mini is available on OpenAI API and OpenRouter. Phi-4 Mini Flash Reasoning is available on NVIDIA NIM. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-11. Data sourced from public model cards and provider documentation.