Level of Development (LOD)
A scale for how developed and how reliable a model element is at a given stage.
Quick Answer
Level of Development (LOD) is a BIM specification that describes how fully a model element's geometry and information are developed, and how much other team members can rely on it. The BIMForum scale runs from LOD 100 to 500, and each level defines what the element represents, such as a concept, a coordinated system, or a field-verified condition.
The Full Picture
A model element can be anything from a simple placeholder box to a detailed assembly with fabrication information. Without an agreed scale, one party may assume a model is ready for quantity takeoff while the author considers it a rough design. LOD gives teams a shared language for how developed each element is, and for what others are allowed to rely on it for.
The widely used reference is the Level of Development Specification published by BIMForum, building on the AIA's LOD definitions. It defines LOD 100, 200, 300, 350, 400, and 500 for building elements, organized by CSI classification. Broadly, lower levels are conceptual or approximate, LOD 300 is a specific element with defined size, shape, and location, LOD 350 adds interfaces with other systems, LOD 400 is fabrication detail, and LOD 500 represents field-verified conditions.
LOD should not be confused with Level of Detail, which is simply how much graphical detail a model shows. Development covers geometry and non-graphic information together, and it also carries the idea of reliability. In practice, teams assign LOD to each element at each project milestone in a model element table, often as part of the BIM execution plan, so authors and users know what to expect.
In preconstruction, LOD sets the limits of what can be done with a model. A model at a low LOD can inform a conceptual estimate but not a bid-ready quantity takeoff, and clash detection is only as meaningful as the development of the elements being compared. Contractors review the stated LOD in the contract documents so they do not price or coordinate against detail the design does not actually provide.
Real Examples
Common Misconceptions
People assume: People assume a higher LOD is always better.
Actually: the right level is the one needed for the purpose and milestone; over-developing elements adds cost without adding value.
People assume: People assume LOD is the same as level of detail.
Actually: level of detail is visual richness, while level of development includes geometry, information, and how far the element can be relied on.
Frequently Asked Questions
What is LOD in BIM?
LOD, or Level of Development, describes how fully a model element's geometry and information are developed and how much others can rely on it. The BIMForum scale runs from LOD 100 to 500.
What is the difference between LOD and LOI?
LOD is the combined development of an element, while LOI, Level of Information, refers specifically to the amount of non-graphic data attached to it. Some standards treat geometry and information as separate measures.
What does LOD 300 mean?
At LOD 300 an element is modeled as a specific system or assembly with defined quantity, size, shape, location, and orientation, and can be measured directly from the model.
What is LOD 350?
LOD 350 is a level, not part of the original AIA series, that adds the interfaces and connections with other building systems so coordination can be done at the element level.
Why does LOD matter to contractors?
It tells them how much they can rely on a model for coordination, takeoff, and fabrication, so they know when to verify against drawings or ask for more development.