Level of Development (LOD)

Level of Development (LOD) is the North American scale for how far a model element has progressed — and, crucially, how far it can be relied on for a given use such as estimating, coordination or fabrication. The concept comes from the AIA's BIM protocol documents (the 2013 G202, since superseded by the AIA's 2022 digital-practice set) and is given practical, element-by-element definitions in the BIMForum LOD Specification. It runs on a numeric scale: LOD 100, 200, 300, 350, 400, 500.

Each step raises both detail and reliability. 100 is a symbolic placeholder; 200 is approximate geometry with general information; 300 is specific geometry, accurate enough for quantities and coordination; 350 adds the physical connections, supports and interfaces with other systems — the detail that makes multidisciplinary clash detection meaningful, especially for MEP; 400 is fabrication-and-assembly detail; and 500 is a field-verified as-built condition. The 350 step is a BIMForum addition, created to bridge design-intent geometry (300) and manufacturer fabrication detail (400). Note the acronym itself: in US practice LOD means Level of Development — reliability — which the BIMForum distinguishes from mere Level of Detail, how much is drawn.

The same acronym means different things elsewhere, a common source of confusion. Under the UK's PAS 1192, "LOD" stood for Level of Detail — geometry alone — banded separately from the Level of Information (LOI), a different meaning and scale from the US Level of Development. Italy, under UNI 11337, uses a letter scale — LOD A–G — and likewise splits it into LOG (geometry) and LOI (information). Above all, ISO 19650 and the level of information need standard (EN 17412-1:2020, now internationalised as ISO 7817-1:2024) deliberately move away from any single global LOD scale toward stating how much information is enough for a specific decision. LOD remains common shorthand on real projects, but the level of information need is its modern successor. In Italian, LOD is rendered as the UNI 11337 livello di sviluppo (LOD A–G, with LOG and LOI).