Training

  1. Start of training
  2. Pre-training, 8KKimi K3not stated8KNTPtext and visionMTPallMTP layer
  3. Pre-training, 64KKimi K3not stated64KNTPtext and visionMTPall
  4. Cooldown, 256KKimi K3not stated256KNTPall
  5. Cooldown, 1MKimi K3not stated1MNTPall
  6. Off this path: Draft model1 stage
  7. The frozen target and the time: not stated. Speculative decoding is used in RL rollouts
  8. Draft-model fine-tuningKimi K3not statednot statedLKdraftMTP → draft
  9. Draft model
  10. SFTKimi K3not statednot statedSFTnot statedMXFP4 experts
  11. Cold-start model
  12. RL: nine expertsKimi K3not stated1MRLKimi K2.5’s, near GRPOnot stated
  13. Nine experts
  14. Where the student starts: not stated
  15. Multi-teacher on-policy distillationKimi K3not statednot statedMOPD9 teachersnot stated
  16. Kimi K3
  • tokens, log scale
  • derived: computed from stated numbers
  • context length
  • all parameters train
  • a part trains
  • all but a part trains
  • NTPdashed: concluded, no source names it
  • not stated by the sources
  • the architecture changes
  • checkpoint
  • checkpoint, weights published
  • a join the sources leave unexplained

Cooldown, 1M

×

Stage · Kimi K3

The last stage of the context curriculum: the window reaches 1M tokens.

Context
1M
Data
long documents and videos; synthetic long-context tasks
Share of training
The long-sequence computation is concentrated “within a small fraction of the overall training budget”

Derived

Objective. The report describes the cooldown as the last two stages of one four-stage curriculum and names no objective for it: next-token prediction is concluded from that, and the report does not state it.

Trained. The report names no part of the model held fixed in the cooldown: that every parameter trains is concluded, and the report does not state it.

Not disclosed Tokens · Steps · Batch · Learning rate · Where each window begins · Number format

Why

Length alone does not give long-range capability: the synthetic data embeds tasks that can be solved only with information scattered across the full 1M context, so attention is trained at that scale. Kimi K3 report §3.4, p. 12

All settings5
Context
1M, the last window of the cooldown phase
Curriculum
Four stages: the window grows from 8K to 64K during pre-training, and from 256K to 1M during the cooldown phase
Positions
None to change: the model has no positional embedding, so the context is extended with no modification of a positional encoding
Data
Long documents and videos, cleaned and upsampled; synthetic long-context data whose tasks need information from across the full 1M context
Share of training
The long-sequence computation is concentrated “within a small fraction of the overall training budget”
Sources1