Mistral-Small-4-119B-2603
Mistral AI · reasoning checkpoint
No base checkpoint is public; facts describe the released post-trained checkpoint.
Open in the comparison table Hugging Face ↗ Paper ↗
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
2026-03-16
Source: blog · Introducing Mistral Small 4; header
Introducing Mistral Small 4 March 16, 2026
Same post: "Mistral Small 4 is released under the Apache 2.0 license".
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
Source: model-card · README.md; Key Features
Multimodal input: Accepts both text and image input, with text output.
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
119B parameters
Source: model-card · README.md; Key Features
119B parameters, with 6.5B activated per token.
Total parameter count as reported by the publisher. See params.note for whether embeddings, MTP heads or vision towers are included.
- Active params
6.5B parameters
Source: model-card · README.md; Key Features
119B parameters, with 6.5B activated per token.
The blog says 6B active (8B including embedding and output layers); the card title says A6B.
Parameters used per token in the forward pass, as reported by the publisher.
- Active non-embedding (stated)
6B parameters
Source: blog · Key architectural details
119B total parameters, with 6B active parameters per token (8B including embedding and output layers).
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
119B parameters
Calculated: embedding + output head + all experts + other weights, mistralai/Mistral-Small-4-119B-2603@a11f36b safetensors headers; reproduces stated total (backbone) 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
1.074B parameters
Calculated: input embedding + output head, mistralai/Mistral-Small-4-119B-2603@a11f36b safetensors headers
Input embedding plus output head (once if tied), counted from the checkpoint.
- Non-emb. params (counted)
117.9B parameters
Calculated: dense + routed backbone weights; excludes input embedding, output head, lookup tables, MTP and other modalities, mistralai/Mistral-Small-4-119B-2603@a11f36b safetensors headers; reproduces stated total (backbone) 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)
3.275B parameters
Calculated: max(sum of dense and routed weights sharing a full layers.<index> tensor path), all experts included, mistralai/Mistral-Small-4-119B-2603@a11f36b 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)
5.559B parameters
Calculated: non-expert weights + routed experts × 4/128, excluding embedding and output head, mistralai/Mistral-Small-4-119B-2603@a11f36b safetensors headers; reproduces stated total (backbone) 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.
- Counting scope
Card's 6.5B active has no stated scope; the blog gives 6B without and 8B with embedding and output layers.
Source: blog · Key architectural details
119B total parameters, with 6B active parameters per token (8B including embedding and output layers).
What the publisher's counts include or exclude (MTP modules, embeddings, vision encoder, n-gram tables).
Shape
- Layers
36
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
131,072
Source: config · /text_config/vocab_size
Embedding table rows (vocab_size in config, may include padding).
- Tied embeddings
No
Source: config · /text_config/tie_word_embeddings
Input embedding and output head share weights.
- d_model / layers
113.778
Calculated: d_model / layers
Width-to-depth ratio, d_model divided by the number of blocks.
Attention
- Token mixers
MLA
Source: code · modeling_mistral4.py; Mistral4Attention docstring
Multi-headed Latent Attention (MLA) from Deepseek V2, with support for rope interleave.
Token-mixing layer types in the backbone, e.g. GQA, MLA, SWA, Gated DeltaNet, Mamba-2, DSA (DeepSeek sparse attention).
- Global-attention layers
36
Source: config · /text_config/num_hidden_layers
Every block uses Mistral4Attention (MLA); /text_config/sliding_window is null.
Layers whose KV cache grows with full context (dense or sparse global attention, MLA). Excludes sliding-window and linear/recurrent layers.
- Query heads
32
Source: config · /text_config/num_attention_heads
Query heads in the global-attention layers.
- Heads × head dim
4,096
Calculated: heads × head_dim
attn.heads × attn.head_dim, the query projection width of global layers.
- QK head dim
128
Source: config · /text_config/qk_nope_head_dim + /text_config/qk_rope_head_dim
configuration_mistral4.py recomputes head_dim and qk_head_dim (both 128 in config) as this sum.
Query/key dimension per head in global-attention layers (for MLA, nope + rope dims).
- V head dim
128
Source: config · /text_config/v_head_dim
Value dimension per head in global layers (MLA v_head_dim; stated for MLA even when equal to the QK head dim).
- MLA KV latent
256
Source: config · /text_config/kv_lora_rank
Width of the compressed KV latent that MLA caches per token per layer.
- MLA Q latent
1,024
Source: config · /text_config/q_lora_rank
Width of the low-rank query projection in MLA; 0 when queries use a full-rank projection.
- Decoupled RoPE dim
64
Source: config · /text_config/qk_rope_head_dim
Width of the shared positional key that MLA caches next to the latent.
- Positional encoding
partial RoPE (MLA decoupled, interleaved, 64 of 128 QK dims)
Source: code · modeling_mistral4.py; Mistral4Attention.forward
q_rot, k_rot = apply_rotary_pos_emb_interleave(q_rot, k_rot, cos, sin)
Config /text_config/rope_interleave is true.
Positional scheme in global layers: RoPE, partial RoPE, NoPE, or mixed per layer type.
- RoPE base
10,000
Source: config · /text_config/rope_parameters/rope_theta
RoPE base frequency of the global layers at release.
- QK norm
No
Source: code · modeling_mistral4.py; Mistral4Attention.forward
q_states = self.q_b_proj(self.q_a_layernorm(self.q_a_proj(hidden_states)))
RMSNorm is applied only to the Q and KV latents; per-head Q/K are not normalized.
Queries and keys are normalized per head before the dot product.
- Attention scaling
queries × (1 + 0.1·ln(1 + ⌊pos/8192⌋)) (Llama-4 style)
Source: code · modeling_mistral4.py; get_llama_4_attn_scale
scaling = 1 + beta * torch.log(1 + torch.floor(positions_ids / max_position_embeddings))
beta = /text_config/rope_parameters/llama_4_scaling_beta (0.1), length = original_max_position_embeddings (8192).
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: config · /text_config/attention_bias
Query/key/value projections have bias terms.
Feed-forward
- Activation
SwiGLU
Source: code · modeling_mistral4.py; Mistral4Experts.forward
current_hidden_states = self.act_fn(gate) * up
Config /text_config/hidden_act is silu.
FFN activation (SwiGLU, GeGLU, ...).
- FFN bias
No
Source: code · modeling_mistral4.py; Mistral4MLP.__init__
self.gate_proj = nn.Linear(self.hidden_size, self.intermediate_size, bias=False)
FFN projections have bias terms.
Mixture of experts
- Routed experts
128
Source: config · /text_config/n_routed_experts
Routed experts per MoE layer.
- Experts per token
4
Source: config · /text_config/num_experts_per_tok
Routed experts selected per token.
- Expert dim
2,048
Source: config · /text_config/moe_intermediate_size
Intermediate width of one routed expert.
- Leading dense layers
0
Source: config · /text_config/first_k_dense_replace
All 36 blocks are MoE; /text_config/intermediate_size (12288) is unused.
Number of initial blocks that use a dense FFN instead of MoE.
- Router score
softmax
Source: code · modeling_mistral4.py; Mistral4TopkRouter.forward
scores = router_logits.softmax(-1)
Gating function over expert logits (softmax, sigmoid).
- Load balancing
Not disclosed
Load-balancing method, with coefficients where disclosed.
- Routed scaling factor
1
Source: config · /text_config/routed_scaling_factor
Multiplier applied to the combined routed-expert output (routed_scaling_factor).
- Renormalize top-k
Yes
Source: config · /text_config/norm_topk_prob
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)
32
Calculated: experts / top_k
Routed experts divided by experts selected per token.
- Active / total
0.0546218
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).
Normalization and stability
- Norm
RMSNorm
Source: code · modeling_mistral4.py; Mistral4DecoderLayer.__init__
self.input_layernorm = Mistral4RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
Normalization layer type in the blocks.
- Norm placement
pre
Source: code · modeling_mistral4.py; Mistral4DecoderLayer.forward
hidden_states = self.input_layernorm(hidden_states)
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.
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
262.1K tokens
Source: model-card · README.md; Key Features
256k context length
Config /text_config/max_position_embeddings is 1,048,576.
Longest context the publisher says the model supports, possibly beyond trained length via RoPE scaling.
- Extension method
YaRN factor 128 over original 8,192 (release config)
Source: config · config.json; text_config.rope_parameters
"factor": 128.0, "llama_4_scaling_beta": 0.1, "mscale": 1.0, "mscale_all_dim": 1.0, "original_max_position_embeddings": 8192,
Training-time context stages are not disclosed. Same dict: rope_type/type yarn, beta_fast 32, beta_slow 1.
How context was extended (stages, RoPE base change, YaRN factor).
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
multilingual text and images: Common Crawl and other public datasets, licensed and third-party datasets, synthetic data, user interaction data (subject to opt-out)
Source: paper · §2.1 Publicly available datasets
The datasets used to train the model include Common Crawl.
§1.3 ticks "More than 10 trillions tokens" for the text training data.
Pretraining data composition as disclosed (domain shares, synthetic fraction, repetition).
- Data cutoff
July 2025
Source: paper · §1.3 Latest date of data acquisition/collection
The latest date of data collection was July 2025.
Pretraining data cutoff date.
KV cache
- KV bytes / token
23,040 bytes
Calculated: kv.bytes_at_context / 131072 tokens; uniform BF16, payload only; quantization overhead excluded. Global KV: 36 × (320 × 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
23,040 bytes
Calculated: 23040 B / 1 tokens (Global KV); uniform BF16, payload only; quantization overhead excluded. Global KV: 36 × (320 × 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
3,545 bytes
Calculated: kv.bytes_per_token (131072 tokens) / (params.active / 1e9); uniform BF16, payload only; quantization overhead excluded. Global KV: 36 × (320 × 16/8) B/entry
kv.bytes_per_token divided by active parameters in billions (131,072 tokens in exports).
- KV at context / B active
464,599,828 bytes
Calculated: kv.bytes_at_context (131072 tokens) / (params.active / 1e9); uniform BF16, payload only; quantization overhead excluded. Global KV: 36 × (320 × 16/8) B/entry
kv.bytes_at_context divided by active parameters in billions (131,072 tokens in exports).
- KV at context
3,019,898,880 bytes
Calculated: 23040 B × 131072 (Global KV); uniform BF16, payload only; quantization overhead excluded. Global KV: 36 × (320 × 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
11
Source: leaderboard · Artificial Analysis model page /models/mistral-small-4, Wayback snapshot 2026-10-19
Mistral Small 4 (Reasoning) scores 11 on the Artificial Analysis Intelligence Index
Variant: Mistral Small 4 (Reasoning). 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).