Warning · IFC Schema
How to fix Imperial length unit
in IFC files
Export in SI metric (millimetres/metres) — imperial length units break interoperability with most IFC/BIM tools.
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No account · No upload · Runs in your browser · 44 validation checks
What it means
The Imperial length unit check
Model LENGTHUNIT is imperial (foot/inch) — IFC interchange requires SI metric units
The fix
How to fix Imperial length unit in your authoring tool
Concrete, tool-specific steps. The check itself is schema-agnostic and works for IFC2x3, IFC4, IFC4x1 and IFC4x3.
| Authoring tool | How to fix |
|---|---|
| Revit | Revit’s internal units are imperial but IFC should be metric. Set Project Units to metric (or confirm the IFC export uses SI/metric) so the file’s IFCSIUNIT is metre-based. |
| ArchiCAD | Set the project Working Units (and Calculation Units) to metric so the IFC schema exports SI length units. |
| Tekla | Switch the environment/role or export settings to metric so the IFC LENGTHUNIT is SI (mm/m). |
| Allplan | Set the length units to metric in the project options so the IFC export uses SI units. |
How it works
Find and fix it in the browser
The whole flow runs client-side — your IFC file never leaves your machine.
01
Open your IFC file
Open IFC Viewer Online and drag & drop your IFC file. It is parsed locally in your browser via WebAssembly — nothing is uploaded.
02
Run the Health Score validation
Run validation. The "Imperial length unit" check (RULE_UNIT_CONSISTENCY) flags every affected element and pinpoints it in the model tree.
03
Re-validate
Re-export from your authoring tool and re-run validation to confirm the issue is resolved and your Health Score improved.
Related checks
Other IFC Schema checks →
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