Step 3.5 Flash vs Step 3.7 Flash
Step 3.5 Flash (2026) and Step 3.7 Flash (2026) are frontier-tier reasoning models from StepFun. Step 3.5 Flash ships a 256k-token context window, while Step 3.7 Flash ships a 256k-token context window. On pricing, Step 3.5 Flash costs $0.10/1M input tokens versus $0.20/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
Step 3.5 Flash is ~100% cheaper at $0.10/1M; pay for Step 3.7 Flash only for vision-heavy evaluation.
Decision scorecard
Local evidence first| Signal | Step 3.5 Flash | Step 3.7 Flash |
|---|---|---|
| Best for | reasoning-heavy apps | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Long context | Coding, RAG, and Agents |
| Context window | 256k | 256k |
| Cheapest output | $0.30/1M tokens | $1.15/1M tokens |
| Provider routes | 1 tracked | 3 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Step 3.5 Flash has the lower cheapest tracked output price at $0.30/1M tokens.
- Local decision data tags Step 3.5 Flash for Long context.
- Step 3.7 Flash has broader tracked provider coverage for fallback and procurement flexibility.
- Step 3.7 Flash uniquely exposes Vision, Multimodal, and Function calling in local model data.
- Local decision data tags Step 3.7 Flash for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Step 3.5 Flash
$155
Cheapest tracked route/tier: OpenRouter
Step 3.7 Flash
$448
Cheapest tracked route/tier: StepFun
Estimated monthly gap: $293. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Step 3.7 Flash is $0.85/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Step 3.7 Flash adds Vision, Multimodal, and Function calling in local capability data.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Step 3.5 Flash is $0.85/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Function calling before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-01-29 | 2026-05-29 |
| Context window | 256k | 256k |
| Parameters | 196B (11B active) | 198B (11B active) |
| Architecture | mixture of experts | mixture of experts |
| License | Open Source | Apache 2.0 |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Step 3.5 Flash | Step 3.7 Flash |
|---|---|---|
| Input price | $0.10/1M tokens | $0.20/1M tokens |
| Output price | $0.30/1M tokens | $1.15/1M tokens |
| Providers |
Capabilities
| Capability | Step 3.5 Flash | Step 3.7 Flash |
|---|---|---|
| Vision | No | Yes |
| Multimodal | No | Yes |
| Reasoning | Yes | Yes |
| Function calling | No | Yes |
| Tool use | No | Yes |
| Structured outputs | No | Yes |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Step 3.7 Flash, multimodal input: Step 3.7 Flash, function calling: Step 3.7 Flash, tool use: Step 3.7 Flash, and structured outputs: Step 3.7 Flash. Both models share reasoning mode, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Step 3.5 Flash lists $0.10/1M input and $0.30/1M output tokens on the cheapest tracked provider, while Step 3.7 Flash lists $0.20/1M input and $1.15/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Step 3.5 Flash lower by about $0.33 per million blended tokens. Availability is 1 providers versus 3, so concentration risk also matters.
Choose Step 3.5 Flash when provider fit and lower input-token cost are central to the workload. Choose Step 3.7 Flash when vision-heavy evaluation and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions.
FAQ
Which has a larger context window, Step 3.5 Flash or Step 3.7 Flash?
Step 3.5 Flash supports 256k tokens, while Step 3.7 Flash supports 256k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Step 3.5 Flash or Step 3.7 Flash?
Step 3.5 Flash is cheaper on tracked token pricing. Step 3.5 Flash costs $0.10/1M input and $0.30/1M output tokens. Step 3.7 Flash costs $0.20/1M input and $1.15/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Step 3.5 Flash or Step 3.7 Flash open source?
Step 3.5 Flash is listed under Open Source. Step 3.7 Flash is listed under Apache 2.0. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Step 3.5 Flash or Step 3.7 Flash?
Step 3.7 Flash has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Step 3.5 Flash or Step 3.7 Flash?
Step 3.7 Flash has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Step 3.5 Flash and Step 3.7 Flash?
Step 3.5 Flash is available on OpenRouter. Step 3.7 Flash is available on StepFun, OpenRouter, and NVIDIA NIM. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-29. Data sourced from public model cards and provider documentation.