Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | Gemini 3 Flash Preview (Reasoning) | Kimi K2.5 (Reasoning) |
|---|---|---|
| Input ($/M tokens) | $0.5 | $0.6 |
| Output ($/M tokens) | $3 | $3 |
Verdict. Gemini 3 Flash Preview (Reasoning) and Kimi K2.5 (Reasoning) split the benchmark comparison evenly at 1–1. The tiebreaker here is price, speed, and what you actually run them on.
Pricing. Both models sit in the budget bracket for output-token pricing. At 1.0× the per-million-token cost, Kimi K2.5 (Reasoning) is meaningfully cheaper if your traffic is output-heavy (long completions, document generation, agent loops). Kimi K2.5 (Reasoning) makes more sense when output volume is low and absolute reasoning quality justifies the premium.
Strengths. Gemini 3 Flash Preview (Reasoning) is strongest on Intelligence Index (38.7). Kimi K2.5 (Reasoning) leads on Coding Index (46.8), Intelligence Index (36.0).
Speed. On throughput, Gemini 3 Flash Preview (Reasoning) generates tokens at 189 tok/s versus 43 tok/s — about 77% faster. On time-to-first-token, Kimi K2.5 (Reasoning) responds in 2840ms vs 6570ms, which matters most for chat-style UIs.
Provider. Google and Kimi sell to overlapping but distinct developer audiences: Google tends to ship frontier reasoning models with premium positioning, while Kimi 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): Gemini 3 Flash Preview (Reasoning) costs $60.00 ($720/year); Kimi K2.5 (Reasoning) costs $63.00 ($756/year). At a smaller 5M-input/2M-output scale (single-developer tool or prototype): Gemini 3 Flash Preview (Reasoning) ≈ $8.50/run, Kimi K2.5 (Reasoning) ≈ $9.00/run. At agent/realtime scale (200M input / 100M output per million requests): Gemini 3 Flash Preview (Reasoning) ≈ $400/run, Kimi K2.5 (Reasoning) ≈ $420/run. Gemini 3 Flash Preview (Reasoning) 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
Gemini 3 Flash Preview (Reasoning) is cheaper overall. Its blended price (3:1 input/output ratio) is $1.13/M tokens vs $1.20/M for Kimi K2.5 (Reasoning).
It's a tie — both models win 1 benchmarks each across 12 evaluated categories. See the detailed benchmark chart above for per-category results.
Gemini 3 Flash Preview (Reasoning) generates tokens faster at 189 tok/s vs 43 tok/s. However, Kimi K2.5 (Reasoning) has lower time-to-first-token (2.84s vs 6.57s).
Choose based on your priorities: Gemini 3 Flash Preview (Reasoning) for lower cost, both perform similarly on benchmarks, and Gemini 3 Flash Preview (Reasoning) for faster generation. For latency-sensitive apps, check the TTFT comparison above.