Kimi K3 vs Claude Sonnet 5.5
Which one to choose
Pick Kimi K3 for agents over very large codebases or long histories, for tasks that include video, and when you want open weights and a selectable thinking level of low, high or max. Pick Claude Sonnet 5.5 for everyday coding agents and computer use where fast replies and fewer steps per task matter more than reasoning depth. The main difference is that Kimi K3 always thinks, while Sonnet 5.5 can cut its up-front thinking.
Pricing comparison
| Kimi K3 | Claude Sonnet 5.5 | |
|---|---|---|
| Model maker | Moonshot | Anthropic |
| Delivery availability | Available | Available |
| Context window | 1M | 1M |
| Max output | 128K | 128K |
| Official price | Input$3.00per 1M tokensOutput$15.00per 1M tokens | Input$2.00per 1M tokensOutput$10.00per 1M tokens |
| TokenLab price | — | Input$0.60per 1M tokensOutput$3.00per 1M tokens |
| Model performance | Collecting data |
|
| Capabilities | JSON modePrompt CacheReasoningTool useVision | JSON modePrompt CacheReasoningTool useVision |
Choose Kimi K3 when
- Your agent works across a large repository or a long running conversation and needs the whole history in view.
- Your input includes recordings or video clips as well as screenshots.
- You want to self-host open weights later, or compare hosted and self-run behaviour of one model.
Choose Claude Sonnet 5.5 when
- You run frequent short coding or browsing turns and want replies without a long thinking phase.
- You automate desktop work from screenshots and want tasks to finish in fewer tool-calling steps.
- You want to lower up-front thinking with the between_tools setting while keeping tool-driven reasoning.
How they differ
| Aspect | Kimi K3 | Claude Sonnet 5.5 |
|---|---|---|
| Thinking behaviour | Thinking is always on, with low, high or max effort. Even a trivial turn goes through the thinking phase. | Thinking can be reduced with the between_tools setting, which skips up-front thinking and speeds up simple replies. |
| Input types | Native image and video input, so a screen recording can be part of the task. | Takes text and images. Video is not an input. |
| Openness | Moonshot publishes the weights, though a model of this size is heavy to run yourself. | A closed Anthropic model; the weights are not published. |
| Tool use | Supports tool calling with dynamic loading, JSON output and prefix continuation. | Batches tool calls well, so tasks finish in fewer steps. Forced tool use returns an error. |
| Sampling settings | Effort is the main dial, with low, high and max levels. | Non-default temperature, top_p or top_k values are rejected, so tuning happens through effort and prompts. |
Summary
- Kimi K3: Input $3.00 / Output $15.00 per 1M tokens; Claude Sonnet 5.5: Input $0.60 / Output $3.00 per 1M tokens. Rates depend on the billing unit, specification, and usage. Compare matching conditions in the model's detailed pricing; a single rate does not determine the total cost.
FAQ
Which is better for agent work, Kimi K3 or Claude Sonnet 5.5?
Kimi K3 suits long-horizon agents with big context and video input. Sonnet 5.5 suits fast, everyday agents with fewer steps per task. Pick by the length of the task and how much latency you can accept.
Does Kimi K3 have a non-thinking mode?
No. Moonshot keeps thinking on and lets you choose low, high or max effort. If you need a model that can skip thinking for simple turns, Sonnet 5.5 is the closer fit.
Can Sonnet 5.5 take video like Kimi K3?
No. Sonnet 5.5 reads text and images only. For video input use Kimi K3, or extract frames from the clip and send them to Sonnet 5.5 as images.
Can one replace the other without prompt changes?
Prompts for the task itself carry over, but request shapes, thinking controls and tool-use rules differ. Retest tool calls and sampling settings before you switch.
Which is cheaper, Kimi K3 or Claude Sonnet 5.5?
Kimi K3: Input $3.00 / Output $15.00 per 1M tokens; Claude Sonnet 5.5: Input $0.60 / Output $3.00 per 1M tokens. Rates depend on the billing unit, specification, and usage. Compare matching conditions in the model's detailed pricing; a single rate does not determine the total cost.
What are the key differences between Kimi K3 and Claude Sonnet 5.5?
Both models share similar capabilities.
Sources
Reviewed Oct 2, 2026