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GPT-OSS 120B

Active Parameters

117B

Context Length

128K

Modality

Text

Architecture

Mixture of Experts (MoE)

License

Apache 2.0

Release Date

5 Aug 2025

Knowledge Cutoff

Jun 2024

System Requirements

VRAM requirements for different quantization methods and context sizes

1,024 tokens

247.28 GB VRAM

Consumer

13x RTX 4090

24GB VRAM

Datacenter

4x NVIDIA A100

80GB VRAM

Apple Silicon

3x Apple M3 Max

128GB VRAM

128,000 tokens

257.11 GB VRAM

Consumer

13x RTX 4090

24GB VRAM

Datacenter

4x NVIDIA A100

80GB VRAM

Apple Silicon

3x Apple M3 Max

128GB VRAM

Architecture Diagram

Input TokensToken EmbeddingPosition: AbsoluteHidden: 2.9k · Context: 128K · Vocab: 201.1kx 36 layersRMSNormPre-AttentionMulti-Head Attention64Q / 8KV heads · SW: 128Head dim: 64+RMSNormPre-FFNSparse MoE FFN (4/128 experts)SwiGLU+Final RMSNormOutput Logits

Evaluation Benchmarks

Rank

#51

BenchmarkScoreRank

0.976

🥉

3

General Knowledge

MMLU

0.9

🥉

3

Graduate-Level QA

GPQA

0.801

26

0.42

28

Professional Knowledge

MMLU Pro

0.79

41

General Text

Text Arena

1352

116

Rankings

Overall Rank

#51

Coding Rank

#71

About GPT-OSS 120B

GPT-OSS 120B is a large open-weight model from OpenAI, designed to operate in data centers and on high-end desktops and laptops. It is developed to support advanced reasoning, agentic tasks, and diverse developer use cases, functioning as a text-only model for both input and output modalities.

Technical Specifications

Attention

Attention Structure

Multi-Head Attention

Attention Heads

64

Key-Value Heads

8

Attention Head Dimension

64

Position Embedding

Absolute Position Embedding

RoPE Theta

150,000

Sliding Window Attention

Yes

Sliding Window Size

128

Sliding Window Ratio

-

Linear Attention

-

Linear Attention Ratio

-

Normalization

RMS Normalization

Activation Function

SwigLU

Dimensions

Hidden Dimension Size

2,880

Number of Layers

36

FFN Intermediate Size (Dense)

2,880

Multi-Token Prediction Heads

-

Tokenizer

Vocabulary Size

201,088

Mixture of Experts

Total Expert Parameters

5.1B

Number of Experts

128

Active Experts

4

Shared Experts

-

FFN Intermediate Size (per Expert)

-

Dense Layers Before MoE

-

About GPT-OSS

Open-weight language models from OpenAI.


Other GPT-OSS Models
GPT-OSS 120B: Specifications and GPU VRAM Requirements