What LOD means in BIM
LOD levels in BIM indicate how far each element of a model can be relied upon: its geometry and the information it carries. A column at LOD 100 is a symbol saying “a column goes here, more or less”. The same column at LOD 400 has enough detail to be fabricated in the workshop.
The scale was born in the mid-2000s as a “model progression specification” and was formalised by the American Institute of Architects in its E202-2008 document, with five levels from 100 to 500. Since 2013 it has been developed by BIMForum with its LOD Specification, which is revised every year, has a Spanish edition and added level 350.
Two ideas before going further:
- LOD is assigned per element, not per model. “An LOD 300 model” is a simplification: walls at 300 and furniture at 100 coexist in the same model.
- More LOD is not better. It is more expensive, slower and produces heavier files. The right LOD is the minimum that supports the decision the model has to inform.
Level of Development is not Level of Detail
The D in LOD is read in two ways, and they do not mean the same thing:
- Level of Detail: how much graphic detail the element has. It is a measure of what you see.
- Level of Development: how far the other parties on the project can rely on the geometry and data of that element.
The BIMForum specification uses the second. An element can have a great deal of graphic detail —a beautiful manufacturer family downloaded from the internet— and a low level of development, because nobody has checked that it is the component that actually goes there. Conversely, a duct modelled as a simple prism can be entirely reliable in position and cross-section.
In the English-speaking world you will also see LOG (Level of Geometry) and LOI (Level of Information) to separate the graphic part from the data part. It is the same idea captured by the European approach we will look at below.
The levels, one by one
The definitions follow the BIMForum LOD Specification, which in turn draws on the language of the AIA E201-2022 document. To see it at a glance, the same window in a wall, level by level:
LOD 100 · Symbol or generic representation
The element may be shown as a symbol or a generic representation, and any data derived from it is considered approximate. It is used for massing studies, site fit and very early estimates.
LOD 200 · Approximate shape and size
The element is represented graphically as a generic system, object or assembly, with approximate quantity, size, shape, location and orientation. A wall is “a wall of about 30 cm”, with no defined layers.
LOD 300 · Measurable as designed
The element is modelled so that its quantity, size, shape, location and orientation can be measured directly from the model. It is the level of detailed design. BIMForum notes that designers rarely model beyond 300: what comes afterwards is contributed by contractors and manufacturers.
LOD 350 · With its interfaces
Everything in LOD 300, and in addition the interfaces with adjacent or dependent elements are also measurable: supports, connections, slab penetrations. It is the level of building services coordination before construction.
LOD 400 · Ready to fabricate
The element has enough detail to be fabricated, assembled and installed. It is the level of shop drawings: steelwork with its connections, ductwork with its special fittings.
LOD 500 · Field verified
Here is the catch. The specification defines it as the representation of an existing or as-built condition, developed through observation, field verification or interpolation, and requires its level of accuracy to be stated or attached. It deserves its own section.
Why LOD 500 is not “more” than LOD 400
Almost every guide presents 500 as the step after 400. The BIMForum specification expressly says the opposite: LOD 500 does not indicate a level higher than LOD 400. It indicates something else: that the geometry has been obtained by observing an existing element instead of designing it.
Practical consequences:
- An as-built can be “LOD 500” and have the geometry of an LOD 200. What 500 says is that it has been measured, not how much detail it has.
- Asking for “as-built LOD 500” and nothing more specifies nothing: it still needs to say with what detail and with what accuracy.
- That is why BIMForum recommends pairing it with the USIBD LOA specification, which sets accuracy in five levels, from LOA10 (over 50 mm) to LOA50 (under 1 mm), and distinguishes the accuracy of the measurement from that of the model.
In a Scan to BIM, what really defines the deliverable is the combination of the two: LOD for the detail of each element and LOA for the tolerance against the point cloud. For example: “architecture LOD 300 · LOA20; structure and building services LOD 300 · LOA30”.
The level of information need (UNE-EN ISO 7817-1)
In Europe the approach is different. Instead of a single numerical scale, the UNE-EN ISO 7817-1:2025 standard —which replaces UNE-EN 17412-1:2021— defines the level of information need: a framework for deciding, for each purpose and each delivery, what information is needed and at what granularity.
The standard starts from four preliminary questions: what the information is needed for, at which milestone it is delivered, who produces it and who receives it, and which objects it refers to. And it divides information into three blocks:
- Geometrical: detail, dimensionality, location, appearance and parametric behaviour.
- Alphanumerical: properties and their values.
- Documentation: data sheets, certificates, drawings, associated reports.
One of its stated aims is to avoid delivering more information than necessary, which is exactly the “LOD 400 for everything” problem. The standard itself advises against using an acronym (LOIN) because it oversimplifies the concept; even so, you will see “LOIN” everywhere.
Does it replace LOD? No. BIMForum describes it as complementary: LOD summarises the geometric reliability of an element in a single figure; the level of information need details what is being asked for and why. In Spanish tender documents it is common to see both.
Which LOD to ask for in an as-built model
When the model comes from a laser scan, LOD is decided the other way round from a new project: not by design stage, but by the decision the model has to support. Some guidelines on what we usually recommend for as-built modelling:
- Refurbishment of a home, commercial unit or office: architecture at LOD 200-300. Walls, slabs, openings and levels well measured; the rest, just what is needed.
- Building rehabilitation: architecture and structure at LOD 300, building services at 200 except those that are to be retained.
- Industry, plant rooms, water infrastructure: services and equipment at LOD 300-350, because the value lies in clashes and routing.
- Heritage: singular geometry does not fit well into standard families. It often pays to keep a low LOD in the model and leave the point cloud as the reference for detail.
- Asset management (facility management): moderate geometric LOD and much more weight on alphanumerical information. Here the level of information need is what counts.
And one rule that saves arguments: what is not in the cloud cannot be in the model at a high LOD. If a suspended ceiling was not opened, whatever is above it is modelled, at most, as a documented assumption.
Quick reference table
| LOD | What it guarantees | Typical use |
|---|---|---|
| 100 | Existence and approximate position | Massing, feasibility |
| 200 | Approximate shape and size | Concept design, simple refurbishment |
| 300 | Measurable geometry as designed | Detailed design, quantity take-off |
| 350 | Plus measurable interfaces | MEP coordination, clash detection |
| 400 | Fabrication and assembly detail | Shop drawings, prefabrication |
| 500 | Geometry observed in the field (accuracy stated separately) | As-built, management of the existing asset |
If you have a tender document in front of you and do not know which LOD matches what is being asked, send it to us. We will translate it into a specific scanning and modelling scope before anyone goes on site.