DeepSeek V3.1 vs Phi 3.5 Mini Instruct
DeepSeek V3.1 (2026) and Phi 3.5 Mini Instruct (2024) are compact production models from DeepSeek and Microsoft Research. DeepSeek V3.1 ships a 64K-token context window, while Phi 3.5 Mini Instruct ships a 128K-token context window. On pricing, DeepSeek V3.1 costs $0.56/1M input tokens versus $0.9/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
DeepSeek V3.1 is ~61% cheaper at $0.56/1M; pay for Phi 3.5 Mini Instruct only for long-context analysis.
Specs
| Released | 2026-03-01 | 2024-08-20 |
| Context window | 64K | 128K |
| Parameters | — | 3.8B |
| Architecture | mixture of experts | decoder only |
| License | Open Source | MIT |
| Knowledge cutoff | - | - |
Pricing and availability
| DeepSeek V3.1 | Phi 3.5 Mini Instruct | |
|---|---|---|
| Input price | $0.56/1M tokens | $0.9/1M tokens |
| Output price | $1.68/1M tokens | $0.9/1M tokens |
| Providers |
Capabilities
| DeepSeek V3.1 | Phi 3.5 Mini Instruct | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: DeepSeek V3.1, multimodal input: DeepSeek V3.1, structured outputs: DeepSeek V3.1, and code execution: DeepSeek V3.1. 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.
For cost, DeepSeek V3.1 lists $0.56/1M input and $1.68/1M output tokens, while Phi 3.5 Mini Instruct lists $0.9/1M input and $0.9/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts DeepSeek V3.1 lower by about $0 per million blended tokens. Availability is 6 providers versus 2, so concentration risk also matters.
Choose DeepSeek V3.1 when coding workflow support, lower input-token cost, and broader provider choice are central to the workload. Choose Phi 3.5 Mini Instruct when long-context analysis and larger context windows 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, DeepSeek V3.1 or Phi 3.5 Mini Instruct?
Phi 3.5 Mini Instruct supports 128K tokens, while DeepSeek V3.1 supports 64K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, DeepSeek V3.1 or Phi 3.5 Mini Instruct?
DeepSeek V3.1 is cheaper on tracked token pricing. DeepSeek V3.1 costs $0.56/1M input and $1.68/1M output tokens. Phi 3.5 Mini Instruct costs $0.9/1M input and $0.9/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is DeepSeek V3.1 or Phi 3.5 Mini Instruct open source?
DeepSeek V3.1 is listed under Open Source. Phi 3.5 Mini Instruct is listed under MIT. 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 vision, DeepSeek V3.1 or Phi 3.5 Mini Instruct?
DeepSeek V3.1 has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, DeepSeek V3.1 or Phi 3.5 Mini Instruct?
DeepSeek V3.1 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.
Where can I run DeepSeek V3.1 and Phi 3.5 Mini Instruct?
DeepSeek V3.1 is available on Microsoft Foundry, Fireworks AI, NVIDIA NIM, Together AI, and AWS Bedrock. Phi 3.5 Mini Instruct is available on Fireworks AI and NVIDIA NIM. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.