LOD 300 vs LOD 400: which level of detail does your project actually need?
Key takeaways
- LOD 350 is the right level for most coordination work: enough resolution to clash hard elements and drive a take-off, without modelling every bracket.
- LOD 400 is only worth its cost when a contractor or supplier is consuming the model for fabrication directly.
- Authoring at LOD 400 typically doubles the modelling cost per discipline.
- A practical progression is LOD 300 at stage 3, LOD 350 for stage 4 coordination, and LOD 400 on selected elements during procurement.
LOD — Level of Development — is one of the most misunderstood acronyms in BIM. Half the industry uses it as a substitute for 'detail', the other half as a substitute for 'accuracy'. The AIA's original definition speaks to neither precisely.
For most coordination work — architecture, structure, MEP federation, clash detection — LOD 350 is the sweet spot. You have enough geometric resolution to clash hard elements and enough information to drive a quantity take-off, without modelling every bracket.
LOD 400 only makes sense when the model is feeding fabrication directly: precast panel layouts, structural steel shop drawings, prefabricated MEP riser modules. The cost of authoring at LOD 400 typically doubles per discipline — only worth it when the contractor or supplier is actually consuming the model.
Our usual recommendation: start at LOD 300 in stage 3, push to LOD 350 for stage 4 coordination, and only escalate specific elements (curtain wall, precast, riser modules) to LOD 400 in the procurement phase.
What each level actually means
LOD 200 is generic geometry with approximate size and location — enough to reserve space and test an arrangement. LOD 300 is specific geometry with accurate dimensions, suitable for design intent and coordination of major elements. LOD 350 adds the interfaces between systems: supports, connections and the parts one trade needs in order to install against another.
LOD 400 adds fabrication and assembly detail, which is why it is a procurement-stage decision rather than a design-stage one. LOD 500 is not a detail level at all — it describes a field-verified as-built condition, which is why quoting it alongside the others confuses more than it clarifies.
Specifying level of development in your EIR
The most common specification mistake is applying a single LOD across an entire model. Different elements justify different levels: a curtain wall or precast panel may warrant LOD 400 while internal partitions in the same building sit comfortably at LOD 300.
Specify by element and by stage rather than by model, and state what the information is for. A modelling team that knows the precast supplier will consume the panel geometry will author it differently from one told only to 'model to LOD 400'.
Frequently asked questions
- Is LOD the same as level of detail?
- No, though the terms are used interchangeably in practice. LOD means Level of Development, which covers how reliable the information is, not merely how much geometric detail is shown. A highly detailed element that is not yet a design commitment is not at a high LOD.
- Does a higher LOD mean a more accurate model?
- Not necessarily. LOD describes how developed and reliable the information is, not its dimensional accuracy. An as-built model derived from a point cloud can be dimensionally accurate at a relatively modest LOD.
- Who decides what LOD a project is modelled to?
- It is set by the client's Employer's Information Requirements and carried into the BIM Execution Plan. Where neither exists, it should be agreed between the client, design team and modelling team before authoring begins.
- What is LOD 500?
- LOD 500 describes a field-verified as-built condition rather than a level of geometric detail. It is best treated as a separate deliverable, typically produced from a survey at handover.