As a pretrain, it's probably somewhere between 4.8 and Mythos (around halfway between?).

I thought about this more and realized this was probably overestimating how good of a pretrain it is (given how good prior models like K2.6 were as pretrains). So I ran some tests.

My quick tests indicated that the Kimi K3 pretrain is around halfway between Opus 4 and Opus 4.5. So ~10 months behind Anthropic. These tests probably understate data improvements, so overall I think it's a similarly good pretrain to Opus 4.5 (~8 months behind). These tests are better at measuring "general pretrain capability" than at incorporating (coding-specific) data quality.

So my claim that "As a pretrain, it's probably somewhere between 4.8 and Mythos (around halfway between?)" seems significantly too bullish on the model!

I think Mythos is a pretty big step up in pretraining, so K3 might be more than 8 months behind on the historical pretraining trend relative to Mythos (as in, Mythos is >>3 months ahead of K3 and Mythos was fully done training ~5 months ago).

Overall, this makes me suspect more of the improvements are due to distillation-type effects and makes me think the full catch-up times would be somewhat longer (if Ant/OpenAI stopped but investment still followed current trends). Minimally, more of the improvement probably lives in post-training/mid-training.

For reference, the same test indicates K2.6 is around halfway between Sonnet 4 and Sonnet 4.5. (And this roughly corresponds to some other similar measures.)

Sorry about the error.