GPT-5.4 Nano vs Phi-4 Mini Flash Reasoning
GPT-5.4 Nano (2026) and Phi-4 Mini Flash Reasoning (2025) are frontier reasoning models from OpenAI and Microsoft Research. GPT-5.4 Nano 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 Nano is safer overall; choose Phi-4 Mini Flash Reasoning when reasoning depth matters.
Decision scorecard
Local evidence first| Signal | GPT-5.4 Nano | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Long context |
| Context window | 400K | 128K |
| Cheapest output | $1.25/1M tokens | - |
| Provider routes | 2 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- GPT-5.4 Nano has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.4 Nano has broader tracked provider coverage for fallback and procurement flexibility.
- GPT-5.4 Nano uniquely exposes Multimodal, Function calling, and Tool use in local model data.
- Local decision data tags GPT-5.4 Nano for Coding, RAG, and Agents.
- Phi-4 Mini Flash Reasoning uniquely exposes Reasoning in local model data.
- 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 Nano
$473
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 Nano 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.
- Phi-4 Mini Flash Reasoning adds Reasoning in local capability data.
- No overlapping tracked provider route is sourced for Phi-4 Mini Flash Reasoning and GPT-5.4 Nano; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Reasoning before moving production traffic.
- GPT-5.4 Nano 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 Nano | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Input price | $0.2/1M tokens | - |
| Output price | $1.25/1M tokens | - |
| Providers |
Capabilities
| Capability | GPT-5.4 Nano | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Vision | No | No |
| Multimodal | Yes | No |
| Reasoning | No | 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 Nano, reasoning mode: Phi-4 Mini Flash Reasoning, function calling: GPT-5.4 Nano, tool use: GPT-5.4 Nano, structured outputs: GPT-5.4 Nano, and code execution: GPT-5.4 Nano. Both models share the core language-model surface, 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 Nano has $0.2/1M 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 Nano when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose Phi-4 Mini Flash Reasoning when reasoning depth 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.
FAQ
Which has a larger context window, GPT-5.4 Nano or Phi-4 Mini Flash Reasoning?
GPT-5.4 Nano 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 Nano or Phi-4 Mini Flash Reasoning open source?
GPT-5.4 Nano 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 Nano or Phi-4 Mini Flash Reasoning?
GPT-5.4 Nano 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 Nano or Phi-4 Mini Flash Reasoning?
Phi-4 Mini Flash Reasoning has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for function calling, GPT-5.4 Nano or Phi-4 Mini Flash Reasoning?
GPT-5.4 Nano 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 Nano and Phi-4 Mini Flash Reasoning?
GPT-5.4 Nano 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.