Claude Haiku 4.5 vs Step 3.5 Flash
Claude Haiku 4.5 (2025) and Step 3.5 Flash (2026) are frontier reasoning models from Anthropic and StepFun. Claude Haiku 4.5 ships a 200k-token context window, while Step 3.5 Flash ships a 256k-token context window. On SWE-bench Verified, Step 3.5 Flash leads by 1.1 pts. On pricing, Step 3.5 Flash costs $0.10/1M input tokens versus $0.80/1M 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 3.5 Flash is ~700% cheaper at $0.10/1M; pay for Claude Haiku 4.5 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Haiku 4.5 | Step 3.5 Flash |
|---|---|---|
| Best for | multimodal apps, tool-calling agents, and provider-routed production | reasoning-heavy apps |
| Decision fit | Coding, RAG, and Agents | Coding, Agents, and Long context |
| Context window | 200k | 256k |
| Cheapest output | $4/1M tokens | $0.30/1M tokens |
| Provider routes | 8 tracked | 1 tracked |
| Shared benchmarks | 1 rows | SWE-bench Verified leader |
Decision tradeoffs
- Claude Haiku 4.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Haiku 4.5 uniquely exposes Vision, Multimodal, and Function calling in local model data.
- Local decision data tags Claude Haiku 4.5 for Coding, RAG, and Agents.
- Step 3.5 Flash holds a shared-benchmark lead on SWE-bench Verified, ahead by 1.1 points.
- Step 3.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- 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 Coding, Agents, and Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Haiku 4.5
$1,640
Cheapest tracked route/tier: AWS Bedrock
Step 3.5 Flash
$155
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $1,485. 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 3.5 Flash is $3.70/1M 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.
- Step 3.5 Flash adds Reasoning in local capability data.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Claude Haiku 4.5 is $3.70/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Reasoning before moving production traffic.
- Claude Haiku 4.5 adds Vision, Multimodal, and Function calling in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-10-01 | 2026-01-29 |
| Context window | 200k | 256k |
| Parameters | — | 196B (11B active) |
| Architecture | decoder only | mixture of experts |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | 2025-02 | - |
Pricing and availability
| Pricing attribute | Claude Haiku 4.5 | Step 3.5 Flash |
|---|---|---|
| Input price | $0.80/1M tokens | $0.10/1M tokens |
| Output price | $4/1M tokens | $0.30/1M tokens |
| Providers |
Capabilities
| Capability | Claude Haiku 4.5 | Step 3.5 Flash |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | No | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Claude Haiku 4.5 | Step 3.5 Flash |
|---|---|---|
| SWE-bench Verified | 73.3 | 74.4 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Claude Haiku 4.5 at 73.3 and Step 3.5 Flash at 74.4, with Step 3.5 Flash ahead by 1.1 points. The largest visible gap is 1.1 points on SWE-bench Verified, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Claude Haiku 4.5, multimodal input: Claude Haiku 4.5, reasoning mode: Step 3.5 Flash, function calling: Claude Haiku 4.5, tool use: Claude Haiku 4.5, structured outputs: Claude Haiku 4.5, and code execution: Claude Haiku 4.5. 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, Claude Haiku 4.5 lists $0.80/1M input and $4/1M 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 $1.60 per million blended tokens. Availability is 8 providers versus 1, so concentration risk also matters.
Choose Claude Haiku 4.5 when coding workflow support and broader provider choice are central to the workload. Choose Step 3.5 Flash when reasoning depth, larger context windows, 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.
FAQ
Which has a larger context window, Claude Haiku 4.5 or Step 3.5 Flash?
Step 3.5 Flash supports 256k tokens, while Claude Haiku 4.5 supports 200k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Haiku 4.5 or Step 3.5 Flash?
Step 3.5 Flash is cheaper on tracked token pricing. Claude Haiku 4.5 costs $0.80/1M input and $4/1M 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 Claude Haiku 4.5 or Step 3.5 Flash open source?
Claude Haiku 4.5 is listed under Proprietary. Step 3.5 Flash is listed under Proprietary. 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, Claude Haiku 4.5 or Step 3.5 Flash?
Claude Haiku 4.5 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, Claude Haiku 4.5 or Step 3.5 Flash?
Claude Haiku 4.5 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 Claude Haiku 4.5 and Step 3.5 Flash?
Claude Haiku 4.5 is available on Microsoft Foundry, Anthropic, Snowflake Cortex, AWS Bedrock, and GCP Vertex AI. Step 3.5 Flash is available on OpenRouter. 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.