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GPT-5 Mini High

Parameters

-

Context Length

400K

Modality

Text

Architecture

Dense

License

Proprietary

Release Date

13 Nov 2025

Knowledge Cutoff

May 2024

Technical Specifications

Attention

Attention Structure

Multi-Head Attention

Attention Heads

-

Key-Value Heads

-

Attention Head Dimension

-

Position Embedding

Absolute Position Embedding

RoPE Theta

-

Sliding Window Attention

-

Sliding Window Size

-

Normalization

-

Activation Function

-

Dimensions

Hidden Dimension Size

-

Number of Layers

-

FFN Intermediate Size (Dense)

-

Multi-Token Prediction Heads

-

Tokenizer

Vocabulary Size

-

GPT-5 Mini High

GPT-5 Mini High is a sophisticated, compact variant within the GPT-5 family, engineered to provide high-level reasoning and instruction following while maintaining a resource-efficient footprint. This model utilizes a dense transformer architecture and is designed as part of a multi-model routing system that dynamically allocates computational resources based on query complexity. It serves as a middle-tier solution, bridging the gap between high-throughput 'Nano' models and the highly deliberative 'Pro' flagship versions, making it suitable for production environments where both intelligence and cost-efficiency are required.

Technically, the model incorporates advanced multi-head attention (MHA) mechanisms and supports a significantly expanded context window of 400,000 tokens. This architectural scale enables the processing of extensive technical documentation, complex codebases, and long-form conversational histories with high fidelity. The model is also natively multimodal, supporting the ingestion of both text and image data through unified modality-specific encoders that feed into a common transformer backbone, allowing for complex cross-modal reasoning tasks.

In practical application, GPT-5 Mini High is optimized for tasks such as agentic workflow management, sophisticated web development, and multi-step mathematical problem-solving. Its design philosophy emphasizes reliable tool use and structured output generation, such as valid JSON, which facilitates integration into automated developer pipelines. By offering 'high' verbosity and reasoning effort levels through the API, it allows developers to fine-tune the trade-off between output quality and response latency for specialized enterprise use cases.

About GPT-5

OpenAI's latest generation of language models featuring advanced reasoning capabilities, extended context windows up to 400K tokens, and specialized variants for coding, general intelligence, and efficiency. GPT-5 series introduces improved thinking modes, superior performance across benchmarks, and variants optimized for different use cases from high-capacity Pro models to efficient Nano models. Features native multimodal understanding, enhanced mathematical reasoning, and state-of-the-art coding abilities through Codex variants.


Other GPT-5 Models

Evaluation Benchmarks

Rank

#64

BenchmarkScoreRank

0.82

19

Agentic Coding

LiveBench Agentic

0.47

24

0.55

27

0.68

30

Web Development

WebDev Arena

1393

40

0.68

41

General Text

Text Arena

1390

57

Rankings

Overall Rank

#64

Coding Rank

#79

Model Integrity

Total Score

D

35 / 100

GPT-5 Mini High Model Integrity Report

Total Score

35

/ 100

D

Audit Note

GPT-5 Mini High exhibits a profile of high functional transparency through its API documentation but remains technically opaque regarding its internal construction. While it provides clear versioning and identity consistency, it fails to disclose critical details about its training data, parameter count, and compute resources. The model's transparency is heavily restricted by its proprietary nature and the absence of a comprehensive technical report.

Upstream

10.0 / 30

Architectural Provenance

3.0 / 10

OpenAI describes GPT-5 Mini High as a dense transformer-based model within a unified routing system. While it is explicitly named as a successor to the 'o-series' and 'mini' variants, there is no public technical paper or detailed documentation regarding its specific training methodology, architectural modifications, or pretraining procedure. Information is limited to high-level descriptions of its 'multi-head attention' and 'modality-specific encoders' without verifiable technical specifications.

Dataset Composition

2.0 / 10

No specific dataset breakdown or sources are disclosed. Documentation mentions the use of 'multi-modal datasets' and 'web search' capabilities, but lacks any information on data proportions, filtering methodologies, or collection processes. The training data is essentially a 'black box' with only vague references to its knowledge cutoff (May 2024 for some variants, September 2024 for others).

Tokenizer Integrity

5.0 / 10

The model supports a 400,000-token context window and 128,000-token output limit, which is well-documented in the API. However, the specific tokenizer architecture, vocabulary size, and training data alignment are not publicly detailed in a technical report. While the tokenizer is accessible via the API for functional use, its internal integrity and development process remain opaque.

Model

15.0 / 40

Parameter Density

2.0 / 10

OpenAI explicitly treats parameter counts as proprietary. While third-party estimates suggest a 'hybrid architecture' or 'intermediate scale,' official documentation provides no verifiable numbers for total or active parameters. The model is marketed as 'compact' and 'resource-efficient' without any quantitative evidence to support these claims.

Training Compute

1.0 / 10

There is zero disclosure regarding the compute resources used to train GPT-5 Mini High. No information is provided regarding GPU/TPU hours, hardware specifications, carbon footprint, or training costs. This information is withheld for competitive reasons, offering no transparency into the environmental or financial impact of the model.

Benchmark Reproducibility

4.0 / 10

While scores for benchmarks like GPQA Diamond (82.8%), IFBench (75.4%), and Humanity's Last Exam (19.7%) are cited in third-party reports and some system cards, OpenAI does not provide the exact evaluation code, prompts, or few-shot examples required for independent reproduction. The lack of a formal technical paper makes it difficult to verify the methodology behind these results.

Identity Consistency

8.0 / 10

The model consistently identifies itself as part of the GPT-5 family in API responses and system prompts. It maintains clear versioning (e.g., gpt-5-mini-2025-08-07) and is transparent about its role as a 'mini' variant within the broader routing system. It generally acknowledges its AI nature and capabilities accurately within the constraints of its system instructions.

Downstream

10.0 / 30

License Clarity

2.0 / 10

The model is governed by a strictly proprietary license. While the terms of use for the API are clear, there is no 'open' component to the weights or source code. The license restricts commercial use to the terms of the OpenAI API agreement, and there is no transparency regarding derivative works or the underlying legal framework of the model's development.

Hardware Footprint

3.0 / 10

As a closed-source API-only model, there is no guidance on the VRAM or hardware requirements for local deployment. While OpenAI provides pricing per million tokens, which serves as a proxy for computational cost, there is no documentation on memory scaling for the 400k context window or the impact of quantization on accuracy for this specific variant.

Versioning Drift

5.0 / 10

OpenAI uses dated snapshots (e.g., 2025-08-07) and provides basic release notes in their Help Center. However, the changelogs are often high-level and lack technical detail on weight changes or specific performance drifts. Users have reported behavioral changes in 'thinking' models that are not always fully documented in the official version history.

GPT-5 Mini High: Model Specifications and Details