If a DXF file imports 25.4 times too large, the problem is almost always a unit mismatch. The design was made in millimeters, but your CAD or CAM software interpreted the geometry as inches.
This is not a broken file by itself. It means the import settings need to match the file units before you toolpath, nest, or cut the project.
Why 25.4 Happens
One inch equals 25.4 millimeters. When software reads a millimeter-based DXF as inches, every dimension becomes 25.4 times larger than intended.
For example, a 100 mm part may appear as 100 inches if the import dialog assumes inches. That is why the design looks massively oversized even though the geometry itself may be correct.
The Correct Fix
The clean fix is to re-import the DXF and select millimeters as the import unit. Do this before scaling, editing, or creating toolpaths.
Recommended order:
- Close the incorrectly imported file or delete the imported geometry.
- Start a new job or new drawing in your CAD/CAM software.
- Set the job units to millimeters if the file was supplied in millimeters.
- Import the DXF again and choose millimeters in the import options.
- Measure one known dimension before cutting.
Manual Scaling If You Cannot Re-Import
If your software does not let you change import units, scale the imported geometry by 0.03937. That is the decimal factor for converting millimeters to inches.
Some programs ask for scale as a percentage. In that case, use 3.937%. Do not enter 3.937 as a decimal scale factor unless your software specifically asks for percent values.
If the File Imports Too Small
The inverse problem can also happen. If an inch-based file is interpreted as millimeters, it may appear 25.4 times too small. In that specific case, the correction factor is 25.4, or 2540% when a program asks for percentage scaling.
Do not apply this larger scale factor unless you are certain the file was interpreted in the wrong direction. Guessing here can turn a small setup error into a bad cut.
Check Before You Cut
Before sending a CNC plasma, laser, router, or waterjet job to the machine, measure a known dimension in the imported file. If the intended width is 300 mm, the imported geometry should measure 300 mm in a millimeter job, or about 11.811 inches in an inch job.
This check matters more than the preview image. A render or thumbnail can look correct while the imported geometry is still in the wrong unit system.
CADtsy CNC File Notes
CADtsy products are digital CNC design files. No physical item, material, or hardware is shipped. Many CADtsy packages include DXF, SVG, and PDF files, but included formats vary by product, so always check the product page before purchase.
For plasma-suitable projects, browse plasma DXF files. For the broader catalog, browse CADtsy CNC cut files.
You can also review how CADtsy digital CNC files work for delivery, file-use, and preparation details.
Choosing between formats? Read DXF vs SVG for CNC cutting before importing a project into CAD or CAM software.