This is an LFM2.5-2.6B fine-tune, produced through P-E-W's Heretic (v1.4.0) abliteration engine with Self-Organizing Maps & Magnitude-Preserving Orthogonal Ablation enabled.
Heretication Results
| Score Metric | Value | Parameter | Value |
|---|---|---|---|
| Refusals | 5/540 | direction_index | per layer |
| KL Divergence | 0.0326 | attn.o_proj.max_weights.0 | 0: 0.66 |
| Initial Refusals | 524/540 | attn.o_proj.max_weights.1 | 1: 1.47 |
| attn.o_proj.max_weights.2 | 2: 1.20 | ||
| attn.o_proj.max_weights.3 | 3: 0.72 | ||
| attn.o_proj.max_weights.4 | 4: 1.32 | ||
| attn.o_proj.max_weight_position | 20.98 | ||
| attn.o_proj.min_weights.0 | 0: 0.45 | ||
| attn.o_proj.min_weights.1 | 1: 0.23 | ||
| attn.o_proj.min_weights.2 | 2: 0.12 | ||
| attn.o_proj.min_weights.3 | 3: 0.66 | ||
| attn.o_proj.min_weights.4 | 4: 0.96 | ||
| attn.o_proj.min_weight_distance | 10.98 | ||
| mlp.down_proj.max_weights.0 | 0: 0.07 | ||
| mlp.down_proj.max_weights.1 | 1: 0.78 | ||
| mlp.down_proj.max_weights.2 | 2: 0.73 | ||
| mlp.down_proj.max_weights.3 | 3: 1.14 | ||
| mlp.down_proj.max_weights.4 | 4: 0.35 | ||
| mlp.down_proj.max_weight_position | 14.01 | ||
| mlp.down_proj.min_weights.0 | 0: 0.03 | ||
| mlp.down_proj.min_weights.1 | 1: 0.07 | ||
| mlp.down_proj.min_weights.2 | 2: 0.46 | ||
| mlp.down_proj.min_weights.3 | 3: 0.33 | ||
| mlp.down_proj.min_weights.4 | 4: 0.25 | ||
| mlp.down_proj.min_weight_distance | 6.00 |
Degree of Heretication
The Heresy Index weighs the resulting model's corruption by the process (KL Divergence & PIQA, Manual Response Eval) and its abolition of doctrine (Refusals) for a final verdict in classification.
| Index Entry | Classification | Analysis |
|---|---|---|
| Absolute Heresy | Near zero overt and secondary refusals with minimal to no model damage | |
| Tainted Heresy | Some residual secondary refusals and/or moderate model damage | |
| Impotent Heresy | Lingering overt refusals and high model damage |
Note: This is an arbitrary and subjective classification inspired by Warhammer 40K, indended to serve as a signpost towards the model's performance.
Appendix
Heretication RitualsEmpty system prompt. Custom dataset.
[Trial 365] Refusals: 3/540, KL divergence: 0.0870
[Trial 328] Refusals: 4/540, KL divergence: 0.0336
Β» [Trial 342] Refusals: 5/540, KL divergence: 0.0326
[Trial 396] Refusals: 6/540, KL divergence: 0.0206
[Trial 413] Refusals: 9/540, KL divergence: 0.0183
[Trial 362] Refusals: 17/540, KL divergence: 0.0174
[Trial 385] Refusals: 30/540, KL divergence: 0.0088
[Trial 220] Refusals: 125/540, KL divergence: 0.0079
[Trial 219] Refusals: 173/540, KL divergence: 0.0054
[Trial 283] Refusals: 363/540, KL divergence: 0.0043
[Trial 69] Refusals: 460/540, KL divergence: 0.0043
[Trial 323] Refusals: 480/540, KL divergence: 0.0038
[Trial 251] Refusals: 494/540, KL divergence: 0.0023
[Trial 205] Refusals: 511/540, KL divergence: 0.0010
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β Benchmark β Metric β T342 β Original model β
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β PIQA β name β piqa β piqa β
β β sample_len β 1838 β 1838 β
β β acc,none β 0.7269 β 0.7307 β
β β acc_stderr,none β 0.0104 β 0.0104 β
β β acc_norm,none β 0.7301 β 0.7296 β
β β acc_norm_stderr,none β 0.0104 β 0.0104 β
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β Benchmark β Metric β T328 β Original model β
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β PIQA β name β piqa β piqa β
β β sample_len β 1838 β 1838 β
β β acc,none β 0.7296 β 0.7307 β
β β acc_stderr,none β 0.0104 β 0.0104 β
β β acc_norm,none β 0.7263 β 0.7296 β
β β acc_norm_stderr,none β 0.0104 β 0.0104 β
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β Benchmark β Metric β T396 β Original model β
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β PIQA β name β piqa β piqa β
β β sample_len β 1838 β 1838 β
β β acc,none β 0.7247 β 0.7307 β
β β acc_stderr,none β 0.0104 β 0.0104 β
β β acc_norm,none β 0.7285 β 0.7296 β
β β acc_norm_stderr,none β 0.0104 β 0.0104 β
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β Benchmark β Metric β T385 β Original model β
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β PIQA β name β piqa β piqa β
β β sample_len β 1838 β 1838 β
β β acc,none β 0.7258 β 0.7307 β
β β acc_stderr,none β 0.0104 β 0.0104 β
β β acc_norm,none β 0.7323 β 0.7296 β
β β acc_norm_stderr,none β 0.0103 β 0.0104 β
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β Benchmark β Metric β T413 β Original model β
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β PIQA β name β piqa β piqa β
β β sample_len β 1838 β 1838 β
β β acc,none β 0.7263 β 0.7307 β
β β acc_stderr,none β 0.0104 β 0.0104 β
β β acc_norm,none β 0.7285 β 0.7296 β
β β acc_norm_stderr,none β 0.0104 β 0.0104 β
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Try LFM β’ Docs β’ LEAP β’ Discord
LFM2.5-2.6B
LFM2.5-2.6B is part of LFM2.5, a family of hybrid models designed for on-device deployment. It builds on the LFM2 architecture with a 128K context window and agentic post-training.
- Best-in-class agent: Competitive with models 4x larger on tool use, instruction following, and multi-step agentic tasks.
- Agentic reinforcement learning: Trained inside the most popular agentic harnesses to improve compatibility.
- Efficient inference: 220 tok/s on an Apple M5 Max and 113 tok/s on an AMD Ryzen CPU, in under 2.5 GB of memory.
Find more information about LFM2.5-2.6B in our blog post.
[!NOTE] π» Demos: Try LFM2.5-2.6B's agentic capabilities in a Hugging Face space without any setup: Research Agent in your browser: helps you research a specific question and generates a summary
ποΈ Model Details
| Model | Parameters | Description |
|---|---|---|
| LFM2.5-2.6B-Base | 2.6B | Pre-trained base model for fine-tuning |
| LFM2.5-2.6B | 2.6B | Post-trained for agentic workloads |
LFM2.5-2.6B is a general-purpose text-only model with the following features:
- Total parameters: 2.69B
- Number of layers: 30 (22 double-gated short convolution blocks + 8 GQA)
- Training budget: 34 trillion tokens
- Vocabulary size: 128,000
- Context length: 131,072 tokens
- Languages: English, Arabic, Chinese, French, German, Italian, Japanese, Korean, Portuguese, Spanish, Vietnamese, Thai, Indonesian, Hindi, Russian, Polish
- Generation parameters:
temperature: 0.1top_k: 50repetition_penalty: 1.1
| Model | Description |
|---|---|
| LFM2.5-2.6B | Original model checkpoint in native format. Best for fine-tuning or inference with Transformers, vLLM, and SGLang. |
| LFM2.5-2.6B-GGUF | Quantized format for llama.cpp and compatible tools. Optimized for CPU inference and local deployment with reduced memory usage. |
| LFM2.5-2.6B-ONNX | ONNX Runtime format for cross-platform deployment. Enables hardware-accelerated inference across diverse environments (cloud, edge, mobile). |
| LFM2.5-2.6B-MLX | MLX format for Apple Silicon. Optimized for fast inference on Mac devices using the MLX framework. |
We recommend using it for agentic workloads, tool use, data extraction, RAG, and long-context workflows. It is not recommended for agentic coding and knowledge-heavy tasks.
Chat Template
LFM2.5 uses a ChatML-like format. See the Chat Template documentation for details. Example:
<|startoftext|><|im_start|>system
You are a helpful assistant trained by Liquid AI.<|im_end|>
<|im_start|>user
What is C. elegans?<|im_end|>
<|im_start|>assistant
You can use tokenizer.apply_chat_template() to format your messages automatically.
[!TIP] π‘ Note: LFM2.5-2.6B is a pure reasoning models that always thinks before it answers. It adds a
<think>tag directly in the chat template when starting an assistant answer.
Tool Use
LFM2.5 supports function calling in four steps:
- Function definition: Provide the list of tools as a JSON object in the system prompt, or use
tokenizer.apply_chat_template()withtools=.... - Function call: By default, LFM2.5 writes Pythonic function calls (a Python list between
<|tool_call_start|>and<|tool_call_end|>special tokens), as the assistant answer. You can override this behavior by asking the model to output JSON function calls in the system prompt. - Function execution: Execute the call and return the result with the
toolrole. - Final answer: LFM2.5 interprets the tool output and returns a plain-text answer addressing the original prompt.
See the Tool Use documentation for the full guide. Example:
<|startoftext|><|im_start|>system
List of tools: [{"name": "get_candidate_status", "description": "Retrieves the current status of a candidate in the recruitment process", "parameters": {"type": "object", "properties": {"candidate_id": {"type": "string", "description": "Unique identifier for the candidate"}}, "required": ["candidate_id"]}}]<|im_end|>
<|im_start|>user
What is the current status of candidate ID 12345?<|im_end|>
<|im_start|>assistant
<|tool_call_start|>[get_candidate_status(candidate_id="12345")]<|tool_call_end|>Checking the current status of candidate ID 12345.<|im_end|>
<|im_start|>tool
[{"candidate_id": "12345", "status": "Interview Scheduled", "position": "Clinical Research Associate", "date": "2023-11-20"}]<|im_end|>
<|im_start|>assistant
The candidate with ID 12345 is currently in the "Interview Scheduled" stage for the position of Clinical Research Associate, with an interview date set for 2023-11-20.<|im_end|>
Training
LFM2.5-2.6B is pre-trained on ~34T tokens, with a mid-training phase that extends the context window to 128K. Post-training then turns the base model into an agent in four stages: supervised fine-tuning (two rounds), per-domain teacher specialization, multi-domain on-policy distillation, and agentic reinforcement learning.
In particular, agentic reinforcement learning allows us to directly train the model inside popular agentic harnesses. It exposes the model to their tools, system prompts, and interaction patterns, helping it work reliably across agent environments.
π Inference
LFM2.5 is supported by many inference frameworks. See the Inference documentation for the full list.
| Name | Description | Docs | Notebook |
|---|---|---|---|
| Transformers | Simple inference with direct access to model internals. | Link | |
| vLLM | High-throughput production deployments with GPU. | Link | |
| llama.cpp | Cross-platform inference with CPU offloading. | Link | |
| MLX | Apple's machine learning framework optimized for Apple Silicon. | Link | β |
| LM Studio | Desktop application for running LLMs locally. | Link | β |
| SGLang | High-throughput production deployments with GPU. | Link | - |
Quick start with Transformers (compatible with transformers>=5.0.0):
from transformers import AutoModelForCausalLM, AutoTokenizer, TextStreamer
model_id = "LiquidAI/LFM2.5-2.6B"
model = AutoModelForCausalLM.from_pretrained(
model_id,
device_map="auto",
dtype="bfloat16",
# attn_implementation="flash_attention_2" <- uncomment on compatible GPU
)
tokenizer = AutoTokenizer.from_pretrained(model_id)
streamer = TextStreamer(tokenizer, skip_prompt=True, skip_special_tokens=True)
prompt = "What is C. elegans?"
input_ids = tokenizer.apply_chat_template(
[{"role": "user", "content": prompt}],
add_generation_prompt=True,
return_tensors="pt",
tokenize=True,
)["input_ids"].to(model.device)
output = model.generate(
input_ids,
do_sample=True,
temperature=0.1,
top_k=50,
repetition_penalty=1.1,
max_new_tokens=512,
streamer=streamer,
)
π§ Fine-Tuning
We recommend fine-tuning LFM2.5 for your specific use case to achieve the best results.
| Name | Description | Docs | Notebook |
|---|---|---|---|
| CPT (Unsloth) | Continued Pre-Training using Unsloth for text completion. | Link | |
| CPT (Unsloth) | Continued Pre-Training using Unsloth for translation. | Link | |
| SFT (Unsloth) | Supervised Fine-Tuning with LoRA using Unsloth. | Link | |
| SFT (TRL) | Supervised Fine-Tuning with LoRA using TRL. | Link | |
| DPO (TRL) | Direct Preference Optimization with LoRA using TRL. | Link | |
| GRPO (TRL) | GRPO with LoRA using TRL. | Link |
π Performance
Benchmarks
We compared LFM2.5-2.6B with relevant sub-10B models on a diverse suite of benchmarks.
| Benchmark | LFM2.5-2.6B (2.6B) | gemma-4-E2B-it (5.1B) | gemma-4-E4B-it (8B) | Qwen3.5-4B (4.7B) | Qwen3.5-9B (9.7B) |
|---|---|---|---|---|---|
| AA Omniscience | -29.50 | -74.47 | -49.03 | -54.30 | -50.43 |
| AIME25 | 51.87 | 26.33 | 34.27 | 49.33 | 56.07 |
| LiveCodeBenchv6 | 59.41 | 54.92 | 63.77 | 60.85 | 69.86 |
| IFBench | 59.17 | 34.08 | 39.24 | 48.40 | 56.47 |
| Multi-IF | 80.07 | 69.44 | 77.35 | 55.67 | 62.55 |
| IFStruct | 85.49 | 64.85 | 76.65 | 36.25 | 78.50 |
| BFCLv4 | 56.88 | 36.98 | 46.39 | 50.56 | 60.13 |
| ToolSandbox | 77.83 | 52.40 | 65.00 | 75.55 | 76.44 |
| ΟΒ³-Bench Banking | 5.67 | 3.35 | 4.12 | 5.45 | 5.15 |
| Claw-Eval average (EN) | 62.85 | 53.14 | 58.02 | 62.28 | 66.53 |
| PinchBench | 68.22 | 44.24 | 55.09 | 71.26 | 71.45 |
| BrowseComp+ (OpenClaw) | 26.89 | 8.31 | 15.90 | 24.46 | 27.23 |
CPU Inference
Due to its efficient LFM2 architecture, LFM2.5-2.6B is the fastest model we tested, with decode speeds of 220 tokens/s on an M5 Max and 113 tokens/s on a Ryzen AI Max+ 395. At 30 tokens/s, it allows you to run capable agents even on a phone.
GPU Inference
LFM2.5-2.6B is the fastest model in its size class, reaching almost 15K output tokens per second at high concurrency, roughly 1.3B tokens per day on a single H100.
π¬ Contact
- Got questions or want to connect? Join our Discord community
- If you are interested in custom solutions with edge deployment, please contact our sales team.
Citation
@article{liquidAI202626B,
author = {Liquid AI},
title = {LFM2.5-2.6B: Agents Everywhere},
journal = {Liquid AI Blog},
year = {2026},
note = {www.liquid.ai/blog/lfm2-5-2-6b},
}
@article{liquidai2025lfm2,
title = {LFM2 Technical Report},
author = {Liquid AI},
journal = {arXiv preprint arXiv:2511.23404},
year = {2025}
}