Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | Step 3.5 Flash 2603 | Mistral Small 3 |
|---|---|---|
| Input ($/M tokens) | $0.1 | $0.1 |
| Output ($/M tokens) | $0.3 | $0.3 |
Verdict. Step 3.5 Flash 2603 wins the overall benchmark matchup 1–0 across 1 overlapping categories, but raw benchmark score is only one input to the decision.
Pricing. Both models sit in the budget bracket for output-token pricing. At 1.0× the per-million-token cost, Mistral Small 3 is meaningfully cheaper if your traffic is output-heavy (long completions, document generation, agent loops). Mistral Small 3 makes more sense when output volume is low and absolute reasoning quality justifies the premium.
Strengths. Step 3.5 Flash 2603 is strongest on Intelligence Index (17.0). Mistral Small 3 leads on Intelligence Index (6.7).
Speed. Throughput is comparable — 146 tok/s vs 155 tok/s — so generation speed shouldn't drive your choice here. Look at the per-benchmark wins instead.
Provider. StepFun and Mistral sell to overlapping but distinct developer audiences: StepFun tends to ship frontier reasoning models with premium positioning, while Mistral 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): Step 3.5 Flash 2603 costs $7.50 ($90/year); Mistral Small 3 costs $7.50 ($90/year). At a smaller 5M-input/2M-output scale (single-developer tool or prototype): Step 3.5 Flash 2603 ≈ $1.10/run, Mistral Small 3 ≈ $1.10/run. At agent/realtime scale (200M input / 100M output per million requests): Step 3.5 Flash 2603 ≈ $50/run, Mistral Small 3 ≈ $50/run.
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.
Data from Artificial Analysis API — 12 benchmarks
Both models have similar pricing. Check the detailed breakdown above for input vs output token costs.
Step 3.5 Flash 2603 wins 1 out of 12 benchmarks compared to 0 for Mistral Small 3. See the detailed benchmark chart above for per-category results.
Mistral Small 3 generates tokens faster at 155 tok/s vs 146 tok/s. However, Mistral Small 3 has lower time-to-first-token (0.74s vs 3.55s).
Choose based on your priorities: both are similarly priced, Step 3.5 Flash 2603 for stronger benchmark performance, and Mistral Small 3 for faster generation. For latency-sensitive apps, check the TTFT comparison above.