“What LOD should we model this at?” is a routine BIM question — yet the term is used surprisingly loosely. Is it about how detailed the shape is? How much information there is? This article sorts LOD out.
- LOD measures how developed a model element is
- It has two meanings: "Detail" (geometric refinement) and "Development" (information reliability)
- LOD 100–400 grade how far the design is settled. LOD 500 is not "above" 400 — it marks geometry built from observing what exists
- "Higher is better" is wrong — the rule is only as much as you need, where you need it
The two meanings of LOD
The acronym often carries two distinct meanings. Separating them clears up most of the confusion.
Geometric refinement
- How detailed the geometry is
- The refinement of "appearance"
Information reliability
- How far the shape + properties are fixed and trustworthy
- Maturity of information you can decide on
The crucial lens is Development (reliability). A pretty 3D (high Detail) with placeholder dimensions or properties can’t justify a purchase order. LOD expresses not just “how fine it looks” but “how far you can trust this information.”
The stages (100–500)
This page follows the most widely referenced framework, the US BIMForum LOD Specification 2025. Terms and numbering differ between countries; the international standard ISO 7817-1 tackles the same problem with a different framework, LOIN (level of information need).
LOD 100
Conceptual — approximate volume and location only.
LOD 200
Approximate — rough shape, size and properties.
LOD 300
Detailed — definite shape, size and properties; a design basis.
LOD 350
Connections — interfaces and clashes with other elements.
LOD 400
Fabrication — usable for construction and fabrication.
LOD 500
Existing / as-built — modelled from observation and field verification, with its accuracy stated.
From 100 to 400, a higher number means a more settled design — and more cost and effort. The levels are cumulative: each includes the requirements of the ones below.
LOD 500 is the exception. BIMForum states that LOD 500 does not indicate a higher level than LOD 400; it indicates that the geometry was determined by observing an existing item rather than designing a future one. It is a different kind of model — measured rather than designed — not the top rung.
Mapping to project phases
In practice LOD tends to rise as the project advances, roughly as below. But BIMForum is explicit that there is no strict correspondence between LODs and design phases: a model at any moment always mixes elements at different LODs. Which element reaches which LOD by when is decided per project, in the BEP.
LOD 100–200
Volume studies and rough exploration. Detail not needed.
LOD 300–350
Definite dimensions and properties; coordinated interfaces.
LOD 400
Detail that holds up for fabrication and construction.
LOD 500
Elements remodelled from survey and field checks — not an extension of the design model.
Common misconceptions
"Higher LOD is better." Wrong. High LOD costs time and money. Modeling every element at LOD 400 during schematic design is hugely wasteful. The right move is to raise only what you need, as much as you need, for the purpose.
"LOD = geometric detail only." Incomplete. Detailed shape with empty properties is still low in information reliability (Development). Remember that the essence of BIM is information.
Summary
- LOD measures how developed a model element is.
- It carries two meanings: Detail (geometric refinement) and Development (information reliability).
- LOD 100–400 grade how settled the design is. LOD 500 marks geometry built from observation — a different kind, not a level above 400.
- Phases and LODs do not map strictly; decide per element and purpose in the BEP.
- Don’t max out everything — raise it only as much as the purpose requires.
Read LOD as “how trustworthy is this information,” not “how fine does it look,” and you avoid over-modeling while still securing the quality you need.