gpt-oss-20b vs Magistral Small 2506
gpt-oss-20b (2025) and Magistral Small 2506 (2025) are frontier reasoning models from OpenAI and MistralAI. gpt-oss-20b ships a 131k-token context window, while Magistral Small 2506 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.
gpt-oss-20b is safer overall; choose Magistral Small 2506 when reasoning depth matters.
Decision scorecard
Local evidence first| Signal | gpt-oss-20b | Magistral Small 2506 |
|---|---|---|
| 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 | $0.14/1M tokens | - |
| Provider routes | 9 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- gpt-oss-20b has the larger context window for long prompts, retrieval packs, or transcript analysis.
- gpt-oss-20b has broader tracked provider coverage for fallback and procurement flexibility.
- gpt-oss-20b uniquely exposes Function calling, Tool use, and Structured outputs in local model data.
- Local decision data tags gpt-oss-20b for RAG, Agents, and Long context.
- Magistral Small 2506 uniquely exposes Reasoning in local model data.
- Local decision data tags Magistral Small 2506 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-20b
$59.00
Cheapest tracked route/tier: OpenRouter
Magistral Small 2506
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.
- Magistral Small 2506 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-20b adds Function calling, Tool use, and Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-08-05 | 2025-06-10 |
| Context window | 131k | 128k |
| Parameters | 20B | 24B |
| Architecture | decoder only | decoder only |
| License | Open Weights | Proprietary |
| Knowledge cutoff | 2025-08 | 2025-06 |
Pricing and availability
| Pricing attribute | gpt-oss-20b | Magistral Small 2506 |
|---|---|---|
| Input price | $0.03/1M tokens | - |
| Output price | $0.14/1M tokens | - |
| Providers |
Capabilities
| Capability | gpt-oss-20b | Magistral Small 2506 |
|---|---|---|
| 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: Magistral Small 2506, function calling: gpt-oss-20b, tool use: gpt-oss-20b, and structured outputs: gpt-oss-20b. 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-20b has $0.03/1M input tokens and Magistral Small 2506 has no token price sourced yet. Provider availability is 9 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-20b when long-context analysis, larger context windows, and broader provider choice are central to the workload. Choose Magistral Small 2506 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. For teams standardizing a stack, that distinction is often the difference between a benchmark win and a reliable deployment.
FAQ
Which has a larger context window, gpt-oss-20b or Magistral Small 2506?
gpt-oss-20b supports 131k tokens, while Magistral Small 2506 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-20b or Magistral Small 2506 open source?
gpt-oss-20b is listed under Open Weights. Magistral Small 2506 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-20b or Magistral Small 2506?
Magistral Small 2506 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-20b or Magistral Small 2506?
gpt-oss-20b 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-20b or Magistral Small 2506?
gpt-oss-20b 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-20b and Magistral Small 2506?
gpt-oss-20b is available on Cloudflare Workers AI, OpenRouter, Fireworks AI, GCP Vertex AI, and NVIDIA NIM. Magistral Small 2506 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.