Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | Phi-4 Mini Instruct | Gemini 3.5 Flash (high) |
|---|---|---|
| Input ($/M tokens) | $0 | $1.5 |
| Output ($/M tokens) | $0 | $9 |
Verdict. Gemini 3.5 Flash (high) takes the aggregate benchmark matchup 2–0 across 2 categories. Real workloads usually care about a handful of specific tasks — see the per-benchmark table above.
Pricing. Pricing varies significantly between these models — check the table above for the exact per-token rates. Many production workloads actually surface input-token cost (retrieval-augmented prompts, code-context windows), so factor both directions.
Strengths. Phi-4 Mini Instruct is strongest on Intelligence Index (5.7), Coding Index (3.8). Gemini 3.5 Flash (high) leads on Coding Index (70.1), Intelligence Index (52.0).
Speed. On throughput, Gemini 3.5 Flash (high) generates tokens at 171 tok/s versus 43 tok/s — about 75% faster. On time-to-first-token, Phi-4 Mini Instruct responds in 830ms vs 27290ms, which matters most for chat-style UIs.
Provider. Microsoft and Google sell to overlapping but distinct developer audiences: Microsoft tends to ship frontier reasoning models with premium positioning, while Google often prices more aggressively. Your existing vendor relationships, billing, and SLA preferences may matter as much as the raw numbers above.
Workload cost. Workload scenarios (per million requests at 30M input + 15M output tokens): Phi-4 Mini Instruct costs $0.00 ($0/year); Gemini 3.5 Flash (high) costs $180.00 ($2160/year). At a smaller 5M-input/2M-output scale (single-developer tool or prototype): Phi-4 Mini Instruct ≈ $0.00/run, Gemini 3.5 Flash (high) ≈ $25.50/run. At agent/realtime scale (200M input / 100M output per million requests): Phi-4 Mini Instruct ≈ $0/run, Gemini 3.5 Flash (high) ≈ $1200/run. Phi-4 Mini Instruct becomes more attractive at higher volume — the absolute per-token pricing difference compounds when you ship at scale.
Recommendation. Both models have legitimate use cases — the right answer depends on whether you are optimizing for benchmark ceiling, latency, or unit cost. Start with the cheaper / faster model, evaluate against your specific task, and only switch if the upgrade shows a meaningful lift.
Head-to-head deltas
Data from Artificial Analysis API — 12 benchmarks
Phi-4 Mini Instruct is cheaper overall. Its blended price (3:1 input/output ratio) is $0.00/M tokens vs $3.38/M for Gemini 3.5 Flash (high).
Gemini 3.5 Flash (high) wins 2 out of 12 benchmarks compared to 0 for Phi-4 Mini Instruct. See the detailed benchmark chart above for per-category results.
Gemini 3.5 Flash (high) generates tokens faster at 171 tok/s vs 43 tok/s. Phi-4 Mini Instruct also has lower time-to-first-token (0.83s vs 27.29s).
Choose based on your priorities: Phi-4 Mini Instruct for lower cost, Gemini 3.5 Flash (high) for stronger benchmark performance, and Gemini 3.5 Flash (high) for faster generation. For latency-sensitive apps, check the TTFT comparison above.