Kimi K2.5 vs Step 3.7 Flash
Kimi K2.5 (2026) and Step 3.7 Flash (2026) compare a coding-specialized model against a standalone API model. Kimi K2.5 ships a 256k-token context window, while Step 3.7 Flash ships a 256k-token context window. On Humanity's Last Exam, Kimi K2.5 leads by 3 pts. On pricing, Step 3.7 Flash costs $0.20/1M input tokens versus $0.44/1M for the alternative. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: Kimi K2.5 is coding-specialized model, while Step 3.7 Flash is standalone API model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | Kimi K2.5 | Step 3.7 Flash |
|---|---|---|
| Product type | Coding-specialized model | Standalone API model |
| Best for | custom coding agents, code generation, and tool loops | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 256k | 256k |
| Cheapest output | $2/1M tokens | $1.15/1M tokens |
| Provider routes | 10 tracked | 3 tracked |
| Shared benchmarks | Humanity's Last Exam leader | 2 rows |
Decision tradeoffs
- Kimi K2.5 holds a shared-benchmark lead on Humanity's Last Exam, ahead by 3 points.
- Kimi K2.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Kimi K2.5 for Coding, RAG, and Agents.
- Step 3.7 Flash holds a shared-benchmark lead on BrowseComp, ahead by 15.2 points.
- Step 3.7 Flash has the lower cheapest tracked output price at $1.15/1M tokens.
- Step 3.7 Flash uniquely exposes Reasoning and Tool use 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.
Kimi K2.5
$852
Cheapest tracked route/tier: OpenRouter
Step 3.7 Flash
$448
Cheapest tracked route/tier: StepFun
Estimated monthly gap: $405. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter and NVIDIA NIM; start route-level A/B tests there.
- Step 3.7 Flash is $0.85/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Step 3.7 Flash adds Reasoning and Tool use in local capability data.
- Provider overlap exists on OpenRouter and NVIDIA NIM; start route-level A/B tests there.
- Kimi K2.5 is $0.85/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Reasoning and Tool use before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-03-15 | 2026-05-29 |
| Context window | 256k | 256k |
| Parameters | 1T (MoE, 384 experts) | 198B (11B active) |
| Architecture | mixture of experts | mixture of experts |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Kimi K2.5 | Step 3.7 Flash |
|---|---|---|
| Input price | $0.44/1M tokens | $0.20/1M tokens |
| Output price | $2/1M tokens | $1.15/1M tokens |
| Providers |
Capabilities
| Capability | Kimi K2.5 | Step 3.7 Flash |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| Function calling | Yes | Yes |
| Tool use | No | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Kimi K2.5 | Step 3.7 Flash |
|---|---|---|
| Humanity's Last Exam | 50.2 | 47.2 |
| BrowseComp | 60.6 | 75.8 |
Deep dive
On shared benchmark coverage, Humanity's Last Exam has Kimi K2.5 at 50.2 and Step 3.7 Flash at 47.2, with Kimi K2.5 ahead by 3 points; BrowseComp has Kimi K2.5 at 60.6 and Step 3.7 Flash at 75.8, with Step 3.7 Flash ahead by 15.2 points. The largest visible gap is 15.2 points on BrowseComp, 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 reasoning mode: Step 3.7 Flash and tool use: Step 3.7 Flash. Both models share vision, multimodal input, function calling, and structured outputs, 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, Kimi K2.5 lists $0.44/1M input and $2/1M 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 3.7 Flash lower by about $0.42 per million blended tokens. Availability is 10 providers versus 3, so concentration risk also matters.
Choose Kimi K2.5 when coding workflow support and broader provider choice are central to the workload. Choose Step 3.7 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.
FAQ
Which has a larger context window, Kimi K2.5 or Step 3.7 Flash?
Kimi K2.5 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, Kimi K2.5 or Step 3.7 Flash?
Step 3.7 Flash is cheaper on tracked token pricing. Kimi K2.5 costs $0.44/1M input and $2/1M 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 Kimi K2.5 or Step 3.7 Flash open source?
Kimi K2.5 is listed under Proprietary. Step 3.7 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, Kimi K2.5 or Step 3.7 Flash?
Both Kimi K2.5 and Step 3.7 Flash expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Kimi K2.5 or Step 3.7 Flash?
Both Kimi K2.5 and Step 3.7 Flash expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Kimi K2.5 and Step 3.7 Flash?
Kimi K2.5 is available on Cloudflare Workers AI, Fireworks AI, OpenRouter, Together AI, and NVIDIA NIM. 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: 2026-06-04. Data sourced from public model cards and provider documentation.