Claude Sonnet 4.5 vs Phi-3 Mini 4k
Claude Sonnet 4.5 (2025) and Phi-3 Mini 4k (2024) are frontier reasoning models from Anthropic and Microsoft Research. Claude Sonnet 4.5 ships a 200k-token context window, while Phi-3 Mini 4k ships a 4k-token context window. On MMLU PRO, Claude Sonnet 4.5 leads by 40.3 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Claude Sonnet 4.5 fits 50x more tokens; pick it for long-context work and Phi-3 Mini 4k for tighter calls.
Decision scorecard
Local evidence first| Signal | Claude Sonnet 4.5 | Phi-3 Mini 4k |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | provider-routed production |
| Decision fit | Coding, RAG, and Agents | Coding and Classification |
| Context window | 200k | 4k |
| Cheapest output | $15/1M tokens | $0.25/1M tokens |
| Provider routes | 8 tracked | 4 tracked |
| Shared benchmarks | MMLU PRO leader | 2 rows |
Decision tradeoffs
- Claude Sonnet 4.5 holds a shared-benchmark lead on MMLU PRO, ahead by 40.3 points.
- Claude Sonnet 4.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Sonnet 4.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Sonnet 4.5 uniquely exposes Vision, Multimodal, and Reasoning in local model data.
- Local decision data tags Claude Sonnet 4.5 for Coding, RAG, and Agents.
- Phi-3 Mini 4k has the lower cheapest tracked output price at $0.25/1M tokens.
- Local decision data tags Phi-3 Mini 4k for Coding and Classification.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Sonnet 4.5
$6,150
Cheapest tracked route/tier: Microsoft Foundry
Phi-3 Mini 4k
$103
Cheapest tracked route/tier: Replicate API
Estimated monthly gap: $6,048. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Microsoft Foundry and Replicate API; start route-level A/B tests there.
- Phi-3 Mini 4k is $14.75/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Reasoning before moving production traffic.
- Provider overlap exists on Microsoft Foundry and Replicate API; start route-level A/B tests there.
- Claude Sonnet 4.5 is $14.75/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Sonnet 4.5 adds Vision, Multimodal, and Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-09-29 | 2024-04-23 |
| Context window | 200k | 4k |
| Parameters | — | 3.8B |
| Architecture | decoder only | decoder only |
| License | Proprietary | MIT(OSI) |
| Openness | Proprietary | Open source |
| Commercial use | Commercial use with conditions | Commercial use allowed |
| Knowledge cutoff | 2025-12 | 2023-10 |
Pricing and availability
| Pricing attribute | Claude Sonnet 4.5 | Phi-3 Mini 4k |
|---|---|---|
| Input price |
| $0.05/1M tokens |
| Output price |
| $0.25/1M tokens |
| Providers |
Capabilities
| Capability | Claude Sonnet 4.5 | Phi-3 Mini 4k |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | No |
| 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
| Benchmark | Claude Sonnet 4.5 | Phi-3 Mini 4k |
|---|---|---|
| MMLU PRO | 86.0 | 45.7 |
| Google-Proof Q&A | 83.4 | 40.9 |
Deep dive
On shared benchmark coverage, MMLU PRO has Claude Sonnet 4.5 at 86 and Phi-3 Mini 4k at 45.7, with Claude Sonnet 4.5 ahead by 40.3 points; Google-Proof Q&A has Claude Sonnet 4.5 at 83.4 and Phi-3 Mini 4k at 40.9, with Claude Sonnet 4.5 ahead by 42.5 points. The largest visible gap is 42.5 points on Google-Proof Q&A, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Claude Sonnet 4.5, multimodal input: Claude Sonnet 4.5, reasoning mode: Claude Sonnet 4.5, function calling: Claude Sonnet 4.5, tool use: Claude Sonnet 4.5, and structured outputs: Claude Sonnet 4.5. 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, Claude Sonnet 4.5 lists tiered pricing: 0-200,001t is $3/1M input and $15/1M output; 200,001t+ is $6/1M input and $22.50/1M output, while Phi-3 Mini 4k lists $0.05/1M input and $0.25/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Phi-3 Mini 4k lower by about $6.49 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 8 providers versus 4, so concentration risk also matters.
Choose Claude Sonnet 4.5 when reasoning depth, larger context windows, and broader provider choice are central to the workload. Choose Phi-3 Mini 4k when provider fit and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Sonnet 4.5 or Phi-3 Mini 4k?
Claude Sonnet 4.5 supports 200k tokens, while Phi-3 Mini 4k supports 4k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Sonnet 4.5 or Phi-3 Mini 4k?
Claude Sonnet 4.5 lists tiered pricing: 0-200,001t is $3/1M input and $15/1M output; 200,001t+ is $6/1M input and $22.50/1M output. Phi-3 Mini 4k lists $0.05/1M input and $0.25/1M output tokens on the cheapest tracked provider. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. Provider discounts or batch pricing can still change the final bill.
Is Claude Sonnet 4.5 or Phi-3 Mini 4k open source?
Claude Sonnet 4.5 is listed under Proprietary. Phi-3 Mini 4k 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, Claude Sonnet 4.5 or Phi-3 Mini 4k?
Claude Sonnet 4.5 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.
Which is better for multimodal input, Claude Sonnet 4.5 or Phi-3 Mini 4k?
Claude Sonnet 4.5 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 Claude Sonnet 4.5 and Phi-3 Mini 4k?
Claude Sonnet 4.5 is available on Microsoft Foundry, Anthropic, Snowflake Cortex, GCP Vertex AI, and AWS Bedrock. Phi-3 Mini 4k is available on Microsoft Foundry, NVIDIA NIM, Baseten API, and Replicate API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.