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 · 38 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
Fix in 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…
04
Fix in ArchiCAD
Set the project Working Units (and Calculation Units) to metric so the IFC schema exports SI length units.
05
Fix in Tekla
Switch the environment/role or export settings to metric so the IFC LENGTHUNIT is SI (mm/m).
06
Fix in Allplan
Set the length units to metric in the project options so the IFC export uses SI units.
07
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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