Inkling-Small
Thinking Machines Lab · reasoning checkpoint
No base checkpoint is public; facts describe the released post-trained checkpoint.
Open in the comparison table Hugging Face ↗ Blog ↗
KV calculations use one sequence at 131,072 tokens and 16-bit cache elements. They include bounded sliding-window caches. This is retained cache payload, not peak prefill memory. The comparison table also offers sourced mixed-precision layouts, including quantization scales.
Release
- Released
2026-07-30
Source: blog · article header
Introducing Inkling-Small Jul 30, 2026
Date the weights (or, if earlier, the technical report) were first made public, YYYY-MM-DD, as dated by the publisher. A Hugging Face repository creation date is used only when no dated publisher page exists, with a note.
- License
apache-2.0
Source: model-card · README.md; YAML front matter
license: apache-2.0
License of the released weights as declared by the publisher (model card metadata or license file), e.g. apache-2.0, mit, or the name of a custom license.
- Input modalities
text + image + audio
Source: model-card · §1 General Information
Inkling-Small is a general-purpose multimodal model that accepts text, image and audio inputs and generates text outputs.
Input modalities of the released checkpoint as the publisher states them, from: text, image, video, audio, joined with ' + ' in that order ("text", "text + image + video").
Parameters
- Total params
276B parameters
Source: model-card · README.md; §3 Model Properties, Parameters
276B total, 12B active
Total parameter count as reported by the publisher. See params.note for whether embeddings, MTP heads or vision towers are included.
- Active params
12B parameters
Source: model-card · README.md; §3 Model Properties, Parameters
276B total, 12B active
Parameters used per token in the forward pass, as reported by the publisher.
- Active non-embedding (stated)
Not disclosed
Active parameters excluding the input embedding and the output head (unembedding). Stated by the publisher, or computed from params.active by subtracting vocab × d_model for each of the embedding and output head that params.active is stated to include (basis inferred, note with the arithmetic). Not disclosed when the scope of params.active is not stated.
- Counted total params
263.7B parameters
Calculated: embedding + output head + all experts + other weights, thinkingmachines/Inkling-Small@8cc5877 safetensors headers; reproduces stated total (MTP+other modalities) and active (with embedding and output head)
Parameters of the text backbone counted from the released checkpoint's safetensors headers (embedding, output head, all experts and other weights; excluding MTP modules, vision/audio towers and n-gram lookup tables). Shown only when the counts reproduce the publisher's stated total and active parameters within 5% under some scope.
- Counted embedding + head
1.647B parameters
Calculated: input embedding + output head, thinkingmachines/Inkling-Small@8cc5877 safetensors headers
Input embedding plus output head (once if tied), counted from the checkpoint.
- Non-emb. params (counted)
262B parameters
Calculated: dense + routed backbone weights; excludes input embedding, output head, lookup tables, MTP and other modalities, thinkingmachines/Inkling-Small@8cc5877 safetensors headers; reproduces stated total (MTP+other modalities) and active (with embedding and output head)
Language backbone weights excluding input embeddings, output head, lookup/Engram tables, MTP modules and vision/audio towers. Equals params.counted_total minus params.counted_embedding. Same validation as params.counted_total.
- Largest layer (counted)
6.538B parameters
Calculated: max(sum of dense and routed weights sharing a full layers.<index> tensor path), all experts included, thinkingmachines/Inkling-Small@8cc5877 safetensors headers
Largest group of language-backbone weights sharing a full layers.<index> tensor path, including every routed expert. Excludes lookup/Engram tables, embeddings, output head, MTP and other modalities. Hybrid checkpoints may store mixers and FFNs as separate layers. All-gather volume also depends on wrapping, sharding and dtype.
- Active non-emb. (counted)
10.35B parameters
Calculated: non-expert weights + routed experts × 6/256, excluding embedding and output head, thinkingmachines/Inkling-Small@8cc5877 safetensors headers; reproduces stated total (MTP+other modalities) and active (with embedding and output head)
Active parameters per token excluding the input embedding and output head, counted from the checkpoint as all non-expert weights plus routed-expert weights × top_k / experts. Same validation as params.counted_total.
Shape
- Layers
42
Source: config · /text_config/num_hidden_layers
Number of transformer blocks in the main backbone (attention or token mixer plus FFN), excluding MTP modules.
- d_model
4,096
Source: config · /text_config/hidden_size
Residual stream width.
- Vocab
201,024
Source: config · /text_config/vocab_size
/text_config/unpadded_vocab_size is 200058.
Embedding table rows (vocab_size in config, may include padding).
- Tied embeddings
No
Source: code · modeling_inkling.py; InklingForConditionalGeneration
are separate tensors in the checkpoints, never tied
Input embedding and output head share weights.
- d_model / layers
97.5238
Calculated: d_model / layers
Width-to-depth ratio, d_model divided by the number of blocks.
Attention
- Token mixers
GQA, SWA
Source: model-card · README.md; §3 Model Properties, Architecture type
Attention is a hybrid of local and global layers.
Token-mixing layer types in the backbone, e.g. GQA, MLA, SWA, Gated DeltaNet, Mamba-2, DSA (DeepSeek sparse attention).
- Layer layout
5 SWA : 1 global
Inferred from the source; see the explanation below.
Source: config · config.json; /text_config/local_layer_ids
"local_layer_ids": [ 0, 1, 2, 3, 4, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40 ]
Config /text_config/local_layer_ids omits 5, 11, 17, 23, 29, 35, 41: global at every 6th layer. /text_config/local_layer_ids gives zero-based SWA indices; other backbone layers use global attention.
Token-mixer order, summarized as a pattern or layer positions. The fact's optional sequence lists each mixer in order; a ratio alone does not establish the order. Auxiliary prediction modules and standalone FFNs are excluded.
- Global-attention layers
7
Inferred from the source; see the explanation below.
Source: model-card · README.md; §3 Model Properties, Architecture type
A 42-layer decoder-only transformer
42 layers minus the 35 SWA layers in /text_config/local_layer_ids.
Layers whose KV cache grows with full context (dense or sparse global attention, MLA). Excludes sliding-window and linear/recurrent layers.
- SWA : global
5
Calculated: attn.local_layers / attn.global_layers
attn.local_layers divided by attn.global_layers, the sliding-window to global interleave ratio (5 for '5 SWA : 1 global').
- Sliding-window layers
35
Source: config · /text_config/local_layer_ids | len
Layers with a fixed attention window.
- Query heads
32
Source: config · /text_config/num_attention_heads
Query heads in the global-attention layers.
- KV heads
8
Source: config · /text_config/num_key_value_heads
Global layers; SWA layers read /text_config/swa_num_key_value_heads (InklingAttention).
Key/value heads in the global-attention layers. Not applicable to MLA, whose cache is a shared latent.
- Heads × head dim
4,096
Calculated: heads × head_dim
attn.heads × attn.head_dim, the query projection width of global layers.
- Q heads / KV head
4
Calculated: heads / kv_heads
attn.heads divided by attn.kv_heads in global layers.
- QK head dim
128
Source: config · /text_config/head_dim
Query/key dimension per head in global-attention layers (for MLA, nope + rope dims).
- Window
512 tokens
Source: config · /text_config/sliding_window_size
Sliding-window size of the local layers.
- SWA KV heads
8
Source: config · /text_config/swa_num_key_value_heads
KV heads in sliding-window layers (stated even when equal to attn.kv_heads).
- SWA query heads
32
Source: config · /text_config/swa_num_attention_heads
InklingAttention reads the swa_* head counts and head dim for hybrid_sliding layers, the global ones otherwise.
Query heads in sliding-window layers (stated even when equal to attn.heads).
- SWA QK head dim
128
Source: config · /text_config/swa_head_dim
Query/key head dimension in sliding-window layers. Value head dimensions may differ; see attn.local_v_head_dim.
- Positional encoding
relative position bias (learned, hidden-state-conditioned, all layers)
Source: code · modeling_inkling.py; InklingAttention.forward
position_bias = self.rel_logits_proj(relative_states, q_positions, kv_positions)
No rotary embedding. InklingRelativeLogits: hidden-state-conditioned bias (d_rel 16), zero beyond rel_extent (1024 on global layers, /text_config/rel_extent; 512 on SWA).
Positional scheme in global layers: RoPE, partial RoPE, NoPE, or mixed per layer type.
- QK norm
Yes
Source: code · modeling_inkling.py; InklingAttention.__init__
self.q_norm = InklingRMSNorm(self.head_dim, eps=config.rms_norm_eps)
Queries and keys are normalized per head before the dot product.
- Attention scaling
1/head_dim; global layers scale queries and position bias by 1 + 0.1·ln(max((pos+1)/128000, 1))
Source: code · modeling_inkling.py; InklingAttention.forward
tau = 1.0 + self.config.log_scaling_alpha * torch.log(
self.scaling = 1.0 / self.head_dim (q/k are RMS-normalized); /text_config/log_scaling_alpha 0.1, /text_config/log_scaling_n_floor 128000.
Query-key scaling when it is not 1/sqrt(head_dim), e.g. query_pre_attn_scalar, length-dependent (SSMax-style) scaling, or value scaling.
- QKV bias
No
Source: code · modeling_inkling.py; InklingAttention.__init__
self.k_proj = nn.Linear(config.hidden_size, self.num_key_value_heads * self.head_dim, bias=False)
Query/key/value projections have bias terms.
- Short conv kernel
4
Source: config · /text_config/sconv_kernel_size
Causal depthwise convolutions on the K and V projections and on the attention and MLP block outputs (InklingShortConvolution; /text_config/use_sconv).
Kernel size of the causal short convolution in linear / SSM layers or attention projections.
Feed-forward
- Activation
SwiGLU
Source: code · configuration_inkling.py; InklingTextConfig
hidden_act: str = "silu"
config.json does not set hidden_act, so the silu default applies; modeling_inkling.py computes act_fn(gate) * up in dense, shared and routed experts.
FFN activation (SwiGLU, GeGLU, ...).
- Dense FFN dim
16,384
Source: config · /text_config/dense_intermediate_size
Intermediate width of the dense FFN layers that are actually executed.
- FFN bias
No
Source: code · modeling_inkling.py; InklingMLP.__init__
self.gate_proj = nn.Linear(self.hidden_size, self.intermediate_size, bias=False)
FFN projections have bias terms.
- Dense FFN / d_model
4
Calculated: ffn.dim / d_model
ffn.dim divided by shape.d_model.
Mixture of experts
- Routed experts
256
Source: config · /text_config/n_routed_experts
Routed experts per MoE layer.
- Experts per token
6
Source: config · /text_config/num_experts_per_tok
Routed experts selected per token.
- Expert dim
2,048
Source: config · /text_config/intermediate_size
With dense_intermediate_size set, intermediate_size is the routed-expert width (configuration_inkling.py __post_init__).
Intermediate width of one routed expert.
- Leading dense layers
2
Source: config · /text_config/dense_mlp_idx
Layers i < dense_mlp_idx are dense (configuration_inkling.py __post_init__).
Number of initial blocks that use a dense FFN instead of MoE.
- Router score
sigmoid
Source: code · modeling_inkling.py; InklingTopkRouter.forward
scores = router_logits.sigmoid()
Config /text_config/gate_activation is not read by the modeling code.
Gating function over expert logits (softmax, sigmoid).
- Load balancing
expert-score correction bias on top-k selection
Source: code · modeling_inkling.py; InklingTopkRouter.forward
scores_for_choice = routed_scores + self.e_score_correction_bias
Bias (/text_config/use_gate_bias) affects selection only; its update rule and any auxiliary loss are not disclosed.
Load-balancing method, with coefficients where disclosed.
- Routed scaling factor
8
Source: config · /text_config/route_scale
Also multiplied by a learned scalar (global_scale, /text_config/use_global_scale); applies to the shared-expert weights as well.
Multiplier applied to the combined routed-expert output (routed_scaling_factor).
- Renormalize top-k
Yes
Source: code · modeling_inkling.py; InklingTopkRouter.forward
topk_weights = torch.exp(topk_log_probs - torch.logsumexp(topk_log_probs, dim=-1, keepdim=True))
Sigmoid scores of the 6 selected routed experts and the 2 shared experts are normalized jointly (shared_expert_sink, /text_config/norm_after_topk).
Selected expert weights are renormalized to sum to 1.
- Expert dim / d_model
0.5
Calculated: moe.expert_dim / d_model
moe.expert_dim divided by shape.d_model.
- Sparsity (experts / top-k)
42.6667
Calculated: experts / top_k
Routed experts divided by experts selected per token.
- Active / total
0.0434783
Calculated: params.active / params.total
params.active divided by params.total.
Multi-token prediction
- MTP depth
Not disclosed
Additional future tokens predicted during pretraining (0 when the model was trained without MTP).
- MTP weights released
Yes
Source: config · model.safetensors.index.json; weight_map
"model.mtp.layers.7.input_proj.weight"
8 MTP layers (/mtp_config/num_nextn_predict_layers); their use in pretraining is not disclosed.
The released checkpoint contains the MTP module weights.
Normalization and stability
- Norm
RMSNorm
Source: code · modeling_inkling.py; InklingDecoderLayer.__init__
self.input_layernorm = InklingRMSNorm(config.hidden_size, config.rms_norm_eps)
Normalization layer type in the blocks.
- Norm placement
pre
Source: code · modeling_inkling.py; InklingDecoderLayer.forward
hidden_states = self.input_layernorm(hidden_states)
Short convolutions on attention and MLP outputs before the residual add.
Pre-norm, post-norm, or sandwich (pre and post).
- Norm epsilon
1e-06
Source: config · /text_config/rms_norm_eps
Epsilon of the block normalization layers.
- Embedding scaling
RMSNorm after embedding
Source: code · modeling_inkling.py; InklingNormedEmbedding.__init__; config /text_config/use_embed_norm
self.embed_norm = InklingRMSNorm(embedding_dim, eps=norm_eps)
Scaling or normalization applied to input embeddings (e.g. × sqrt(d_model), RMSNorm after embedding).
- Output logit scaling
final hidden state ÷ 16 before the LM head
Source: code · modeling_inkling.py; InklingForConditionalGeneration.forward
hidden_states = outputs[0] / self.config.text_config.logits_mup_width_multiplier
/text_config/logits_mup_width_multiplier is 16.0.
Scaling applied to output logits other than a softcap (e.g. muP-style width multiplier).
Context length
- Pretraining context
Not disclosed
Sequence length of the main pretraining stage.
- Trained context
Not disclosed
Longest sequence length trained on after context extension.
- Advertised context
1.049M tokens
Source: blog · Introduction
a context window of up to 1M tokens
Config /text_config/model_max_length is 1048576.
Longest context the publisher says the model supports, possibly beyond trained length via RoPE scaling.
Pretraining recipe
- Pretraining tokens
Not disclosed
Tokens seen in pretraining including annealing and context extension, as reported.
- Optimizer
Not disclosed
Optimizer used for the bulk of parameters.
- Peak LR
Not disclosed
Peak learning rate of the main pretraining stage.
- Final LR
Not disclosed
Learning rate at the end of the decay.
- LR schedule
Not disclosed
Learning-rate schedule shape with phase boundaries.
- Warmup
Not disclosed
Warmup length in steps or tokens.
- Batch size
Not disclosed
Global batch size, including any batch-size ramp: sequences × sequence length (token total), or the token total alone when only that is stated.
- Weight decay
Not disclosed
Decoupled weight decay coefficient.
- Adam betas
Not disclosed
(beta1, beta2) of the Adam-family optimizer or its AdamW fallback.
- Grad clip
Not disclosed
Global gradient-norm clipping threshold.
- Training precision
Not disclosed
Matmul precision of pretraining (BF16, FP8 recipe, NVFP4 recipe) with the scaling granularity where disclosed. Never inferred from the released checkpoint dtype.
- Data mix
text, images, audio, video
Source: model-card · README.md; §4 Training
Training data includes a broad variety of content types, including text, images, audio, video.
The announcement says the pre-training data mix and recipe were changed from Inkling's.
Pretraining data composition as disclosed (domain shares, synthetic fraction, repetition).
- Hardware
NVIDIA GB300 NVL72
Source: blog · Introduction
trained on NVIDIA GB300 NVL72 systems
Accelerators used for pretraining, count and duration where stated.
- Accelerators
GB300
Accelerator count and type for the main pretraining run, as the count with thousands separators and the chip's short name ("2,048 H800", "2,048 GH200"). A stated range or bound stays as stated ("2,048–4,096 GH200").
Scaling & HP transfer
- Parametrization
μP (final hidden state ÷ 16 width multiplier before the LM head)
Source: code · configuration_inkling.py; InklingTextConfig docstring, logits_mup_width_multiplier
muP width multiplier the final hidden states are divided by before the language modeling head.
/text_config/logits_mup_width_multiplier is 16.0.
Width/depth parametrization used to transfer hyperparameters: SP (standard), μP, CompleteP, u-μP, depth-μP, with the multipliers that differ from SP. Only when stated.
KV cache
- KV bytes / token
29,232 bytes
Calculated: kv.bytes_at_context / 131072 tokens; uniform BF16, payload only; quantization overhead excluded. Global KV: 7 × (2048 × 16/8) B/entry; SWA KV: 35 × (2048 × 16/8) B/entry
Retained KV cache divided by context length, including bounded SWA caches and indexer keys. Exports use uniform BF16 at 131,072 tokens. The website can select uniform payload precision (no quantization overhead) or sourced component formats (including scales and documented padding). This is cache payload, not peak prefill memory or persistent prefix storage.
- Global KV bytes / token
28,672 bytes
Calculated: 28672 B / 1 tokens (Global KV); uniform BF16, payload only; quantization overhead excluded. Global KV: 7 × (2048 × 16/8) B/entry; SWA KV: 35 × (2048 × 16/8) B/entry
Long-context global KV bytes per token, including indexer keys; excludes bounded SWA caches. Compression rates and cross-layer cache reuse are included. Exports use uniform BF16; the website's storage selector also applies here. This is the field to compare with global-KV figures in reports, using the matching storage recipe.
- KV bytes / token / B active
2,436 bytes
Calculated: kv.bytes_per_token (131072 tokens) / (params.active / 1e9); uniform BF16, payload only; quantization overhead excluded. Global KV: 7 × (2048 × 16/8) B/entry; SWA KV: 35 × (2048 × 16/8) B/entry
kv.bytes_per_token divided by active parameters in billions (131,072 tokens in exports).
- KV at context / B active
319,291,392 bytes
Calculated: kv.bytes_at_context (131072 tokens) / (params.active / 1e9); uniform BF16, payload only; quantization overhead excluded. Global KV: 7 × (2048 × 16/8) B/entry; SWA KV: 35 × (2048 × 16/8) B/entry
kv.bytes_at_context divided by active parameters in billions (131,072 tokens in exports).
- KV at context
3,831,496,704 bytes
Calculated: 28672 B × 131072 (Global KV) + 143360 B × min(131072, 512) (SWA KV); uniform BF16, payload only; quantization overhead excluded. Global KV: 7 × (2048 × 16/8) B/entry; SWA KV: 35 × (2048 × 16/8) B/entry
Retained KV cache for one sequence at the selected context, including SWA windows and indexer keys. Exports use uniform BF16 at 131,072 tokens. Excludes recurrent state, compressor tail state, draft/MTP caches, temporary prefill tensors, allocator metadata and persistent prefix snapshots. Does not estimate peak prefill or total serving memory.
Evaluations
- AA Intelligence Index
26
Source: leaderboard · Artificial Analysis model page /models/inkling-small, Wayback snapshot 2026-10-19
Inkling Small scores 26 on the Artificial Analysis Intelligence Index
Variant: Inkling Small. Index v4.3.2.
Artificial Analysis Intelligence Index v4.3.2 of the post-trained model, from a dated Wayback snapshot of its Artificial Analysis page. The note names the variant (reasoning setting).