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o3-mini vs Phi-3.5 Medium

A complete head-to-head: pricing, context window, benchmarks, modality coverage, and openness, with a programmatic verdict synthesized from the underlying data.

Updated

o3-mini specs · Phi-3.5 Medium specs
Verdict by category
  • Priceo3-mini

    o3-mini publishes pricing ($4.40 / 1M output tokens) while Phi-3.5 Medium does not.

  • Context windowo3-mini

    o3-mini accepts 200K tokens vs 128K, 1.6× the room for long documents and codebases.

  • BenchmarksTie

    No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores.

  • ModalitiesTie

    Both handle text.

  • OpennessPhi-3.5 Medium

    Phi-3.5 Medium ships open weights (MIT); o3-mini is API-only.

On balance o3-mini edges ahead, winning 2 of 5 categories against Phi-3.5 Medium's 1. o3-mini publishes pricing ($4.40 / 1M output tokens) while Phi-3.5 Medium does not. o3-mini accepts 200K tokens vs 128K, 1.6× the room for long documents and codebases.

No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores. Both target the same set of modalities (text), so the deciding factors are price, context, and raw quality. Phi-3.5 Medium ships open weights (MIT); o3-mini is API-only.

o3-mini is the newer of the two, released 5 months after Phi-3.5 Medium, which usually means a more recent knowledge cutoff and updated safety post-training. o3-mini is usually picked for reasoning and math workloads, while Phi-3.5 Medium sees more deployments in on device and edge deployment. If pricing matters more than every last benchmark point, run the numbers in the calculator below before committing.

Side-by-side specs

Speco3-miniPhi-3.5 Medium
ProviderOpenAIMicrosoft
ReleasedJan 2025Aug 2024
Modalitiestexttext
Context window200K tokens128K tokens
Max output,,
Input · 1M$1.10 / 1M tokensPricing not published
Output · 1M$4.40 / 1M tokensPricing not published
Knowledge cutoff2023-10,
Open weightsNoYes (MIT)
API availableYesYes

Pricing at scale

What you'd actually pay at typical workloads. Numbers come from each model's published per-million-token rates.

  • Light usage, 100k in / 50k out per day$9.90 vs ,
  • Heavy usage, 1M in / 500k out per day$99.00 vs ,
  • RAG workload, 5M in / 200k out per day$191 vs ,

Light usage, 100k in / 50k out per day: pricing not directly comparable (one or both models are missing public per-token rates). Heavy usage, 1M in / 500k out per day: pricing not directly comparable (one or both models are missing public per-token rates). RAG workload, 5M in / 200k out per day: pricing not directly comparable (one or both models are missing public per-token rates).

Price calculator

Estimated spend for the listed models at your usage. Numbers are derived from each model's published per-million-token rates.

  • o3-mini$0.330
  • Phi-3.5 MediumPricing unavailable

Benchmarks compared

Only sourced numbers. Where a benchmark is missing for one model we show the available value rather than fabricating the other.

o3-miniPhi-3.5 Medium
  • MMLU,78.9
  • GPQA79.7
Pick o3-mini if

o3-mini fits when…

  • Reasoning at mid-tier cost
  • Fast for a thinking model
  • Long-context tasks, handles 200K tokens vs 128K for Phi-3.5 Medium.
Pick Phi-3.5 Medium if

Phi-3.5 Medium fits when…

  • MIT license
  • 128k context
  • Strong reasoning at 14B
  • Self-hosting and on-prem requirements, open weights (MIT).
Don't want either?

Consider GPT-5.5

OpenAI's mid-cycle GPT-5 refresh, improved reasoning, tool use, and multimodal grounding over the 2025 launch.

See GPT-5.5 specso3-mini vs GPT-5.5Phi-3.5 Medium vs GPT-5.5

Frequently asked

  • Is o3-mini or Phi-3.5 Medium cheaper?
    Per-token pricing isn't published for at least one of these models, check each model's spec page for current rates.
  • Which has the larger context window?
    o3-mini accepts 200K tokens vs 128K for Phi-3.5 Medium.
  • Is o3-mini or Phi-3.5 Medium better for coding?
    Both o3-mini and Phi-3.5 Medium are competitive on coding benchmarks. See each model's individual spec page for HumanEval and SWE-bench scores where published. For an opinionated pick, consult our Best LLM for Coding ranking.
  • Are either of these models open source?
    Phi-3.5 Medium ships open weights (MIT). o3-mini is API-only.
  • When were o3-mini and Phi-3.5 Medium released?
    o3-mini was released by OpenAI on 2025-01-31. Phi-3.5 Medium was released by Microsoft on 2024-08-20.
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