Downgrade IFC
Convert an IFC4 model to the widely supported IFC2x3 format.
An IFC4 to IFC2x3 converter that runs online, in your browser — upload an IFC4 (or IFC4X1) file, run the downgrade, and download a valid IFC2x3 file. No desktop software to install, no conversion scripts to maintain.
Plenty of production tools still speak IFC2x3 only: older Navisworks and Solibri deployments, facility-management imports, and government submission portals that mandate IFC2x3 Coordination View. When your authoring tool exports IFC4 and the receiving system refuses it, this tool converts the file you already have — and tells you exactly what changed on the way down.
When to reach for it: When an older tool, FM import, or submission portal only accepts IFC2x3 and your authoring software exports IFC4.
What you get: An IFC2x3 file converted from the IFC4 original. Tessellated geometry is re-encoded as B-rep, IFC4-only classes are mapped to IFC2x3 equivalents, and everything that couldn't be represented is listed in the run log.
Example: Deliver an IFC2x3 Coordination View file to a checker or portal that doesn't accept IFC4.
What the converter changes — and what it reports
Downgrading is inherently lossy: IFC4 defines geometry, classes, attributes and enum values that IFC2x3 simply doesn't have. Instead of failing or silently dropping data, the converter maps each difference to its closest IFC2x3 expression and lists every change in the run log:
- Tessellated geometry (IfcPolygonalFaceSet, IfcTriangulatedFaceSet) is re-encoded as classic faceted B-rep — the exact same vertices and faces, so nothing changes visually. The file gets larger; that's inherent to IFC2x3.
- IFC4-only classes are mapped to their IFC2x3 equivalents: IfcPipeSegment becomes IfcFlowSegment, IfcDoorType becomes IfcDoorStyle, and classes with no counterpart (like IfcShadingDevice) become proxies with the original class name preserved in ObjectType.
- Enum values added in IFC4 are clamped to USERDEFINED with the original value kept in the element's type string — IFC's own convention for out-of-vocabulary values.
- IFC4-only attributes and value types are dropped or preserved as text; every drop is counted and reported so you can judge whether the loss matters.
Safety: your source file is never modified
The downgrade writes a new IFC2x3 output file; the IFC4 file you uploaded stays untouched. If too little of the model survives the schema boundary (under half the entities), the tool refuses to pretend success and returns your original file with an explanation instead — you never get a silently empty output.
GlobalIds, names, property sets and the spatial structure are carried through, so GUID-based workflows (model compare, issue tracking) keep working across the conversion.
How downgrade ifc works
- Upload your IFC4 file
- Click Run to convert the schema
- Download the IFC2x3 file
Under the hood
BIMCamel parses IFC files in the browser using the open-source web-ifc engine and renders models with @thatopen/components + three.js. Heavy operations (clean / optimise / validate / convert) run on disposable server-side workers using the same web-ifc stack plus our own .NET pipeline; results stream back to your browser as soon as they're ready. Uploads sit on our servers only as long as your tier's retention window allows and are never used to train AI.
Frequently asked questions
Is IFC4 to IFC2x3 conversion lossless?
No converter can make it lossless — IFC2x3 can't express everything IFC4 can. Geometry survives visually (tessellated face sets are re-encoded as B-rep), and IFC4-only classes are mapped to their nearest IFC2x3 equivalent with the original class name preserved. Attributes and enum values that don't exist in IFC2x3 are dropped or clamped, and every single change is listed in the run log.
Why would I convert IFC4 down to IFC2x3?
Because the receiving system demands it: older Navisworks or Solibri versions, FM imports, and several public-sector submission portals still require IFC2x3 Coordination View. Downgrading the file you have is faster than hunting for the original authoring model and an export licence.
Will the IFC2x3 file be bigger than the IFC4 original?
Often, yes. IFC4's tessellated geometry is a compact indexed format; IFC2x3 needs one entity per vertex, loop and face to say the same thing. The shape is identical — the encoding is just more verbose. Run the Optimize tool on the result if size matters.
Which source schemas are supported?
IFC4 and IFC4X1. IFC4X2/X3 files can't be loaded for conversion yet — export IFC4 from your authoring tool first if you're on a 4.3 pipeline.
Can I convert IFC2x3 up to IFC4 too?
Yes — that's the separate Upgrade IFC tool. The two are mirror operations and both keep your uploaded original untouched.
What's the maximum IFC file size?
Up to 25 MB as a guest, 100 MB with a free account, 500 MB on Pro, and 1 GB on Team. The caps are on upload size only — every tool itself is available on every tier.
What happens to my file after processing?
Your file is uploaded over HTTPS and processed on our servers. Guest uploads are stream-only — the working files are deleted as soon as your download finishes. Free accounts keep results for 7 days; Pro keeps them 90 days and Team 180 days. Files are never shared with third parties or used to train AI.
Is Downgrade IFC free?
Yes. Downgrade IFC is free to use — guests get 3 runs a day with 25 MB uploads, and a free account raises that to 10 runs a day with 100 MB uploads. No trial clock, no watermarks.