“What LOD is this model?” is one of the most common questions on a BIM project — and one of the most misunderstood. Level of Development (LOD) is simply a shared language for how detailed and reliable a model element is at a given stage. It stops people assuming a rough concept model is fabrication-ready, and vice versa. Here’s each level in plain terms.
What LOD actually measures
LOD describes how complete and trustworthy an individual element is — not how pretty it looks. A helpful distinction: Level of Detail is the input (how much it’s drawn), while Level of Development is the reliable output (how much you can count on it). The widely used framework comes from the American Institute of Architects (AIA), which defined LOD 100, 200, 300, 400, and 500; the BIMForum working group later added LOD 350 to cover cross-trade coordination.
One important nuance: LOD isn’t tied rigidly to design phases, and different elements in the same model can sit at different LODs at the same time. It’s a way to describe a deliverable precisely, not a calendar.
LOD 100 — Conceptual
Basic massing: overall shape, area, height, volume, orientation. The element may be a symbol or generic placeholder, and related information (like cost per square metre) is often derived from other elements. Good for feasibility studies.
LOD 200 — Approximate
Generic systems and components with approximate quantity, size, shape, and location. Non-graphic information may be attached. You can plan with it, but you can’t build from it.
LOD 300 — Detailed
Accurate geometry with specific size, shape, location, and orientation — suitable for construction documents. Non-geometric data can be embedded too. This is the level most design-stage construction drawings target.
LOD 350 — Coordinated
Everything in LOD 300, plus how elements interface with each other — supports, connections, and interactions between systems. This is the level created specifically to enable cross-discipline clash detection and coordination.
LOD 400 — Fabrication
Detailed enough for fabrication and assembly: shop drawings and prefabrication, including mounting and installation detail. This is where detailers and fabricators work.
LOD 500 — As-Built
A field-verified representation of what was actually built. This is where the model’s value carries into operations and maintenance — facility teams rely on it as the record of the real installation.
Why it matters
Agreeing LOD expectations up front prevents a lot of pain: it enables proper interdisciplinary coordination, more accurate cost and schedule, fewer errors, and far more predictability about what each deliverable will actually contain. When a contract says “structural model at LOD 350 by the coordination milestone,” everyone knows exactly what they’re getting.
And remember the earlier distinction from this series: LOD describes how reliable an element is, while BIM dimensions describe the type of information in the model. The two work together.
Part of our BIM fundamentals series. Next: what IFC is and why open BIM matters.