Model reference · open weights

OLMo-2-0425

LLMs allenai Text gen 2 builds Open weights 891k dl/mo

OLMo-2-0425 is an open-weight language model from allenai. OLMo-2-0425-1B (FP32) weighs 3.0 GB; the smallest configuration that runs it is RTX 3060 12 GB.

  • OLMo-2-0425 is a 1.5B parameter transformer language model developed by Allen Institute for AI for text generation tasks.
  • It features a context length of 4096 tokens and is trained on English data.
  • The model is released under the Apache 2.0 license.

Summary of the allenai/OLMo-2-0425-1B model card, 2026-10-01

What it is

Released byallenai
Released2025-04-17
Parameters1.5B
VRAM3.0 GB for the weights

What it runs on

Memory and cards for OLMo-2-0425-1B (FP32)

3.0 GBweights, file size
131 MBcache per 1K tokens
633 MBruntime overhead, at least
4,096 tokenscontext max
CardRequests at onceContext maxMemory
4K each
RTX 3060 12 GB14all 4K11.6 GB
RTX 4060 Ti 16 GB21all 4K15.4 GB
RTX 3090 24 GB36all 4K23.4 GB
RTX 4090 24 GB36all 4K23.4 GB
RTX 5090 32 GB51all 4K31.0 GB
L40S 48 GB75all 4K44.0 GB
A100 80 GB138all 4K78.2 GB
H100 80 GB132all 4K78.1 GB
RTX PRO 6000 Blackwell 96 GB161all 4K93.8 GB
DGX Spark (GB10) 128 GB unified186all 4K107 GB
H200 141 GB243all 4K138 GB
B200 180 GB314all 4K176 GB
Memory needed at each load
Requests at once4K tokens each
14.1 GB
56.3 GB
87.9 GB
1612.2 GB
3220.8 GB
6438.0 GB

One card, with vLLM's small-card settings.

Builds

Sizes, precisions & builds

BuildParamsPrecisionWeightsSmallest setup
OLMo-2-0425-1B (above) ↗ 1.5BFP32 3.0 GBRTX 3060 12 GB
OLMo-2-0425-1B-Instruct ↗ 1.5BBF16 3.0 GBRTX 3060 12 GB

From the model card

What allenai says about OLMo-2-0425

Read the model card

Model Details

Model Card for OLMo 2 1B

We introduce OLMo 2 1B, the smallest model in the OLMo 2 family. OLMo 2 was pre-trained on OLMo-mix-1124 and uses Dolmino-mix-1124 for mid-training.

OLMo 2 is the latest in a series of Open Language Models designed to enable the science of language models. We have released all code, checkpoints, logs, and associated training details on GitHub.

SizeTraining TokensLayersHidden SizeAttention HeadsContext Length
OLMo 2-1B4 Trillion162048164096
OLMo 2-7B4 Trillion324096324096
OLMo 2-13B5 Trillion405120404096
OLMo 2-32B6 Trillion645120404096

The core models released in this batch include the following:

StageOLMo 2 1BOLMo 2 7BOLMo 2 13BOLMo 2 32B
Base Modelallenai/OLMo-2-0425-1Ballenai/OLMo-2-1124-7Ballenai/OLMo-2-1124-13Ballenai/OLMo-2-0325-32B
SFTallenai/OLMo-2-0425-1B-SFTallenai/OLMo-2-1124-7B-SFTallenai/OLMo-2-1124-13B-SFTallenai/OLMo-2-0325-32B-SFT
DPOallenai/OLMo-2-0425-1B-DPOallenai/OLMo-2-1124-7B-DPOallenai/OLMo-2-1124-13B-DPOallenai/OLMo-2-0325-32B-DPO
Final Models (RLVR)allenai/OLMo-2-0425-1B-Instructallenai/OLMo-2-1124-7B-Instructallenai/OLMo-2-1124-13B-Instructallenai/OLMo-2-0325-32B-Instruct
Reward Model (RM)allenai/OLMo-2-1124-7B-RM(Same as 7B)

Installation

OLMo 2 1B is supported in transformers v4.48 or higher:

pip install transformers>=4.48

If using vLLM, you will need to install from the main branch until v0.7.4 is released. Please

Inference

You can use OLMo with the standard HuggingFace transformers library:

from transformers import AutoModelForCausalLM, AutoTokenizer
olmo = AutoModelForCausalLM.from_pretrained("allenai/OLMo-2-0425-1B")
tokenizer = AutoTokenizer.from_pretrained("allenai/OLMo-2-0425-1B")
message = ["Language modeling is "]
inputs = tokenizer(message, return_tensors='pt', return_token_type_ids=False)
# optional verifying cuda
# inputs = {k: v.to('cuda') for k,v in inputs.items()}
# olmo = olmo.to('cuda')
response = olmo.generate(**inputs, max_new_tokens=100, do_sample=True, top_k=50, top_p=0.95)
print(tokenizer.batch_decode(response, skip_special_tokens=True)[0])
>> 'Language modeling is  a key component of any text-based application, but its effectiveness...'

For faster performance, you can quantize the model using the following method:

AutoModelForCausalLM.from_pretrained("allenai/OLMo-2-0425-1B",
    torch_dtype=torch.float16,
    load_in_8bit=True)  # Requires bitsandbytes

The quantized model is more sensitive to data types and CUDA operations. To avoid potential issues, it's recommended to pass the inputs directly to CUDA using:

inputs.input_ids.to('cuda')

We have released checkpoints for these models. For pretraining, the naming convention

Quoted from the model card on Hugging Face. The full card is behind the Hugging Face link above.

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