I have written many articles about the accuracy of BIM models before. However, since many colleagues still have questions and are unclear about the divisions of BIM model accuracy, today I will explain how BIM model accuracy is classified and what the different Levels of Detail (LOD) mean.
What is BIM Model Accuracy? The Level of Detail (LOD) is a standardized classification defined by organizations such as the British AEC (UK) and the American Institute of Architects (AIA). According to the AIA, BIM model accuracy is divided into five stages: LOD 100, LOD 200, LOD 300, LOD 400, and LOD 500. Each stage specifies the required level of detail and accuracy for the model components. Below is an explanation of each LOD stage:
LOD 100
LOD 100 primarily supports early project volume assessments by evaluating the overall area, height, volume, location, and orientation of the project. At this stage, actual project details are generally not considered; only the volume and general form are represented. The following image illustrates a schematic of LOD 100 model accuracy. Models at this level are typically used for preliminary planning, visualization concepts, and basic cost estimation. The information included is minimal, usually limited to a few annotations that provide the owner with a rough idea of the project’s size, volume, and shape.
LOD 200
LOD 200 incorporates most building components, including approximate quantities, sizes, appearances, locations, and orientations. At this stage, non-graphical data can be added to components. Major project elements such as walls, floors, ceilings, roofs, and openings are included. However, the exact materials and styles are not yet clearly defined. Some component dimensions may be established, while others remain undefined. For example, openings on walls or roofs might not yet be classified as doors, windows, or skylights at this level. The thickness, spatial configuration, and project dimensions are roughly outlined. Components represent their approximate positions within the project, enabling analysis of presentation effects, component selection, and cost estimation based on area, volume, and quantity.
LOD 300
At LOD 300, components are represented with precise parameters, including quantity, size, appearance, position, and orientation. While internal materials or exact object details might still be missing, specific data such as reference annotations, constraints, or specification tables can be attached to generate construction documents. The accuracy at this level supports detailed system analysis and enables the production of construction documents and more accurate cost estimates. Currently, most BIM workflows use LOD 300 as a standard. It provides sufficient detail to display individual object characteristics but does not include the depth of information required for facility management or maintenance.
LOD 400
LOD 400 builds upon LOD 300 by including detailed information such as 2D design views, assembly sequences, and manufacturing data. Model components at this level have enough precision to produce construction documents used directly on-site. This level allows for more accurate model analysis and includes precise unit cost data. The key difference between LOD 300 and LOD 400 lies in the amount and type of information embedded in the components, including whether 2D plans are integrated or externally referenced. The image below illustrates the level of detail typical for an LOD 400 model.
LOD 500
LOD 500 represents the highest level of accuracy, showing as-built conditions with the most precise model details. However, such detailed models are not commonly required for general purposes. LOD 500 models are typically used for specialized, highly detailed component views. In many projects, LOD 500 models are not mandatory, as much of the information at this level is not utilized by architects. Components at this stage are often created or provided by equipment manufacturers rather than architects and are tailored to specific project needs.
That concludes the explanation on how BIM model accuracy is divided and the meaning of each LOD level. I hope this article helps clarify these concepts for everyone!
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