o3 Mini vs Phi-3 Mini 4k
o3 Mini (2025) and Phi-3 Mini 4k (2024) are frontier reasoning models from OpenAI and Microsoft Research. o3 Mini ships a 200k-token context window, while Phi-3 Mini 4k ships a 4k-token context window. On MMLU PRO, o3 Mini leads by 33.4 pts. On pricing, Phi-3 Mini 4k costs $0.05/1M input tokens versus $1.10/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Phi-3 Mini 4k is ~2100% cheaper at $0.05/1M; pay for o3 Mini only for coding workflow support.
Decision scorecard
Local evidence first| Signal | o3 Mini | Phi-3 Mini 4k |
|---|---|---|
| Best for | reasoning-heavy apps, tool-calling agents, and provider-routed production | provider-routed production |
| Decision fit | Coding, RAG, and Agents | Coding and Classification |
| Context window | 200k | 4k |
| Cheapest output | $4.40/1M tokens | $0.25/1M tokens |
| Provider routes | 4 tracked | 4 tracked |
| Shared benchmarks | MMLU PRO leader | 2 shared |
Decision tradeoffs
- o3 Mini holds a shared-benchmark lead on MMLU PRO, ahead by 33.4 points.
- o3 Mini has the larger context window for long prompts, retrieval packs, or transcript analysis.
- o3 Mini uniquely exposes Reasoning, JSON / Tool use, and Structured outputs in local model data.
- Local decision data tags o3 Mini 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.
o3 Mini
$1,980
Cheapest tracked route/tier: OpenRouter
Phi-3 Mini 4k
$103
Cheapest tracked route/tier: Replicate API
Estimated monthly gap: $1,878. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for o3 Mini and Phi-3 Mini 4k; plan for SDK, billing, or endpoint changes.
- Phi-3 Mini 4k is $4.15/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning, JSON / Tool use, and Structured outputs before moving production traffic.
- No overlapping tracked provider route is sourced for Phi-3 Mini 4k and o3 Mini; plan for SDK, billing, or endpoint changes.
- o3 Mini is $4.15/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- o3 Mini adds Reasoning, JSON / Tool use, and Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-01-31 | 2024-04-23 |
| Context window | 200k | 4k |
| Parameters | — | 3.8B |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | MITOSI-approved |
| Openness | Proprietary | Open source |
| Weights | Not released | Unknown |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | 2025-04 | 2023-10 |
Pricing and availability
| Pricing attribute | o3 Mini | Phi-3 Mini 4k |
|---|---|---|
| Input price | $1.10/1M tokens | $0.05/1M tokens |
| Output price | $4.40/1M tokens | $0.25/1M tokens |
| Providers |
Capabilities
| Capability | o3 Mini | Phi-3 Mini 4k |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | Yes | No |
| JSON / Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | o3 Mini | Phi-3 Mini 4k |
|---|---|---|
| MMLU PRO | 79.1 | 45.7 |
| Google-Proof Q&A | 79.7 | 40.9 |
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.