gpt-oss-120b vs Phi-4 Mini Flash Reasoning
gpt-oss-120b (2025) and Phi-4 Mini Flash Reasoning (2025) are frontier reasoning models from OpenAI and Microsoft Research. gpt-oss-120b ships a 131k-token context window, while Phi-4 Mini Flash Reasoning ships a 128k-token context window. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads. It focuses on practical selection signals rather than broad model-family marketing.
Phi-4 Mini Flash Reasoning is safer overall; choose gpt-oss-120b when long-context analysis matters.
Decision scorecard
Local evidence first| Signal | gpt-oss-120b | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Best for | tool-calling agents and provider-routed production | reasoning-heavy apps |
| Decision fit | RAG, Agents, and Long context | Long context |
| Context window | 131k | 128k |
| Cheapest output | $0.18/1M tokens | - |
| Provider routes | 10 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- gpt-oss-120b has the larger context window for long prompts, retrieval packs, or transcript analysis.
- gpt-oss-120b has broader tracked provider coverage for fallback and procurement flexibility.
- gpt-oss-120b uniquely exposes Function calling, Tool use, and Structured outputs in local model data.
- Local decision data tags gpt-oss-120b for RAG, Agents, and Long context.
- 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 route or tier on this page.
gpt-oss-120b
$76.20
Cheapest tracked route/tier: OpenRouter
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
- Provider overlap exists on NVIDIA NIM; start route-level A/B tests there.
- Check replacement coverage for Function calling, Tool use, and Structured outputs before moving production traffic.
- Phi-4 Mini Flash Reasoning adds Reasoning in local capability data.
- Provider overlap exists on NVIDIA NIM; start route-level A/B tests there.
- Check replacement coverage for Reasoning before moving production traffic.
- gpt-oss-120b adds Function calling, Tool use, and Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-08-05 | 2025-12-01 |
| Context window | 131k | 128k |
| Parameters | 120B | 3.8B |
| Architecture | decoder only | decoder only |
| License | Open Source | Proprietary |
| Knowledge cutoff | 2025-08 | 2025-02 |
Pricing and availability
| Pricing attribute | gpt-oss-120b | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Input price | $0.04/1M tokens | - |
| Output price | $0.18/1M tokens | - |
| Providers |
Capabilities
| Capability | gpt-oss-120b | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | No | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on reasoning mode: Phi-4 Mini Flash Reasoning, function calling: gpt-oss-120b, tool use: gpt-oss-120b, and structured outputs: gpt-oss-120b. 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-oss-120b has $0.04/1M input tokens and Phi-4 Mini Flash Reasoning has no token price sourced yet. Provider availability is 10 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-oss-120b when long-context analysis, 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. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, gpt-oss-120b or Phi-4 Mini Flash Reasoning?
gpt-oss-120b supports 131k 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-oss-120b or Phi-4 Mini Flash Reasoning open source?
gpt-oss-120b is listed under Open Source. Phi-4 Mini Flash Reasoning is listed under Proprietary. 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 reasoning mode, gpt-oss-120b 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-oss-120b or Phi-4 Mini Flash Reasoning?
gpt-oss-120b 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.
Which is better for tool use, gpt-oss-120b or Phi-4 Mini Flash Reasoning?
gpt-oss-120b has the clearer documented tool use signal in this comparison. If tool use is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run gpt-oss-120b and Phi-4 Mini Flash Reasoning?
gpt-oss-120b is available on Cloudflare Workers AI, OpenRouter, Together AI, Fireworks AI, and GCP Vertex AI. 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: 2026-05-22. Data sourced from public model cards and provider documentation.