Llama 4 Scout 17B vs Step 3.5 Flash
Llama 4 Scout 17B (2025) and Step 3.5 Flash (2026) are frontier reasoning models from AI at Meta and StepFun. Llama 4 Scout 17B ships a 10m-token context window, while Step 3.5 Flash ships a 256k-token context window. On pricing, Step 3.5 Flash costs $0.10/1M input tokens versus $0.17/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Step 3.5 Flash is ~70% cheaper at $0.10/1M; pay for Llama 4 Scout 17B only for long-context analysis.
Decision scorecard
Local evidence first| Signal | Llama 4 Scout 17B | Step 3.5 Flash |
|---|---|---|
| Best for | multimodal apps and long-context analysis | reasoning-heavy apps |
| Decision fit | RAG, Long context, and Vision | Long context |
| Context window | 10m | 256k |
| Cheapest output | $0.66/1M tokens | $0.30/1M tokens |
| Provider routes | 1 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Llama 4 Scout 17B has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Llama 4 Scout 17B uniquely exposes Multimodal and Structured outputs in local model data.
- Local decision data tags Llama 4 Scout 17B for RAG, Long context, and Vision.
- Step 3.5 Flash has the lower cheapest tracked output price at $0.30/1M tokens.
- Step 3.5 Flash uniquely exposes Reasoning in local model data.
- Local decision data tags Step 3.5 Flash for Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Llama 4 Scout 17B
$301
Cheapest tracked route/tier: AWS Bedrock
Step 3.5 Flash
$155
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $146. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Llama 4 Scout 17B and Step 3.5 Flash; plan for SDK, billing, or endpoint changes.
- Step 3.5 Flash is $0.36/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Multimodal and Structured outputs before moving production traffic.
- Step 3.5 Flash adds Reasoning in local capability data.
- No overlapping tracked provider route is sourced for Step 3.5 Flash and Llama 4 Scout 17B; plan for SDK, billing, or endpoint changes.
- Llama 4 Scout 17B is $0.36/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Reasoning before moving production traffic.
- Llama 4 Scout 17B adds Multimodal and Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-10-01 | 2026-01-29 |
| Context window | 10m | 256k |
| Parameters | 17 | 196B (11B active) |
| Architecture | - | mixture of experts |
| License | Open Source | Open Source |
| Knowledge cutoff | 2024-08 | - |
Pricing and availability
| Pricing attribute | Llama 4 Scout 17B | Step 3.5 Flash |
|---|---|---|
| Input price | $0.17/1M tokens | $0.10/1M tokens |
| Output price | $0.66/1M tokens | $0.30/1M tokens |
| Providers |
Capabilities
| Capability | Llama 4 Scout 17B | Step 3.5 Flash |
|---|---|---|
| Vision | No | No |
| Multimodal | Yes | No |
| Reasoning | No | Yes |
| Function calling | No | No |
| Tool use | No | No |
| Structured outputs | Yes | No |
| 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 multimodal input: Llama 4 Scout 17B, reasoning mode: Step 3.5 Flash, and structured outputs: Llama 4 Scout 17B. Both models share the core language-model surface, 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, Llama 4 Scout 17B lists $0.17/1M input and $0.66/1M output tokens on the cheapest tracked provider, while Step 3.5 Flash lists $0.10/1M input and $0.30/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Step 3.5 Flash lower by about $0.16 per million blended tokens. Availability is 1 providers versus 1, so concentration risk also matters.
Choose Llama 4 Scout 17B when long-context analysis and larger context windows are central to the workload. Choose Step 3.5 Flash when reasoning depth and lower input-token cost 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, Llama 4 Scout 17B or Step 3.5 Flash?
Llama 4 Scout 17B supports 10m tokens, while Step 3.5 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, Llama 4 Scout 17B or Step 3.5 Flash?
Step 3.5 Flash is cheaper on tracked token pricing. Llama 4 Scout 17B costs $0.17/1M input and $0.66/1M output tokens. Step 3.5 Flash costs $0.10/1M input and $0.30/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Llama 4 Scout 17B or Step 3.5 Flash open source?
Llama 4 Scout 17B is listed under Open Source. Step 3.5 Flash is listed under Open Source. 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 multimodal input, Llama 4 Scout 17B or Step 3.5 Flash?
Llama 4 Scout 17B 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.
Which is better for reasoning mode, Llama 4 Scout 17B or Step 3.5 Flash?
Step 3.5 Flash has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Llama 4 Scout 17B and Step 3.5 Flash?
Llama 4 Scout 17B is available on AWS Bedrock. Step 3.5 Flash is available on OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Continue comparing
Last reviewed: 2026-05-29. Data sourced from public model cards and provider documentation.