Kimi K2 Thinking vs o3
Kimi K2 Thinking (2025) and o3 (2025) are frontier-tier reasoning models from Moonshot AI and OpenAI. Kimi K2 Thinking ships a 256K-token context window, while o3 ships a 128K-token context window. On pricing, Kimi K2 Thinking costs $0.6/1M input tokens versus $1/1M 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.
Kimi K2 Thinking is ~67% cheaper at $0.6/1M; pay for o3 only for coding workflow support.
Specs
| Released | 2025-01-01 | 2025-03-31 |
| Context window | 256K | 128K |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Unknown |
| Knowledge cutoff | - | - |
Pricing and availability
| Kimi K2 Thinking | o3 | |
|---|---|---|
| Input price | $0.6/1M tokens | $1/1M tokens |
| Output price | $2.5/1M tokens | $4/1M tokens |
| Providers |
Capabilities
| Kimi K2 Thinking | o3 | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on code execution: o3. Both models share reasoning mode 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 Thinking lists $0.6/1M input and $2.5/1M output tokens, while o3 lists $1/1M input and $4/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Kimi K2 Thinking lower by about $0.73 per million blended tokens. Availability is 5 providers versus 3, so concentration risk also matters.
Choose Kimi K2 Thinking when long-context analysis, larger context windows, and lower input-token cost are central to the workload. Choose o3 when coding workflow support 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. It also helps separate model capability from provider packaging, which can change cost and latency. For teams standardizing a stack, that distinction is often the difference between a benchmark win and a reliable deployment.
FAQ
Which has a larger context window, Kimi K2 Thinking or o3?
Kimi K2 Thinking supports 256K tokens, while o3 supports 128K 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 Thinking or o3?
Kimi K2 Thinking is cheaper on tracked token pricing. Kimi K2 Thinking costs $0.6/1M input and $2.5/1M output tokens. o3 costs $1/1M input and $4/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Kimi K2 Thinking or o3 open source?
Kimi K2 Thinking is listed under Proprietary. o3 is listed under Unknown. 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 reasoning mode, Kimi K2 Thinking or o3?
Both Kimi K2 Thinking and o3 expose reasoning mode. 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 structured outputs, Kimi K2 Thinking or o3?
Both Kimi K2 Thinking and o3 expose structured outputs. 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.
Where can I run Kimi K2 Thinking and o3?
Kimi K2 Thinking is available on Fireworks AI, GCP Vertex AI, NVIDIA NIM, AWS Bedrock, and OpenRouter. o3 is available on OpenAI API, OpenRouter, and OpenAI Batch API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-04-27. Data sourced from public model cards and provider documentation.