Claude 3.5 Sonnet vs Step 3.7 Flash
Claude 3.5 Sonnet (2024) and Step 3.7 Flash (2026) are frontier-tier reasoning models from Anthropic and StepFun. Claude 3.5 Sonnet ships a 200k-token context window, while Step 3.7 Flash ships a 256k-token context window. On pricing, Step 3.7 Flash costs $0.20/1M input tokens versus $3/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Step 3.7 Flash is ~1400% cheaper at $0.20/1M; pay for Claude 3.5 Sonnet only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude 3.5 Sonnet | Step 3.7 Flash |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 200k | 256k |
| Cheapest output | $15/1M tokens | $1.15/1M tokens |
| Provider routes | 6 tracked | 3 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Claude 3.5 Sonnet has broader tracked provider coverage for fallback and route flexibility.
- Claude 3.5 Sonnet uniquely exposes Code execution in local model data.
- Local decision data tags Claude 3.5 Sonnet for Coding, RAG, and Agents.
- Step 3.7 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Step 3.7 Flash has the lower cheapest tracked output price at $1.15/1M tokens.
- 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.
Claude 3.5 Sonnet
$6,150
Cheapest tracked route/tier: GCP Vertex AI
Step 3.7 Flash
$448
Cheapest tracked route/tier: StepFun
Estimated monthly gap: $5,703. 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 $13.85/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Code execution before moving production traffic.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Claude 3.5 Sonnet is $13.85/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude 3.5 Sonnet adds Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2024-06-20 | 2026-05-29 |
| Context window | 200k | 256k |
| Parameters | 70B | 198B (11B active) |
| Architecture | Decoder Only | Mixture of Experts |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2024-04 | - |
Pricing and availability
| Pricing attribute | Claude 3.5 Sonnet | Step 3.7 Flash |
|---|---|---|
| Input price | $3/1M tokens | $0.20/1M tokens |
| Output price | $15/1M tokens | $1.15/1M tokens |
| Providers |
Capabilities
| Capability | Claude 3.5 Sonnet | Step 3.7 Flash |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
Continue comparing
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Last reviewed: 2026-07-26. Data sourced from public model cards and provider documentation.