DXF Unit Converter
LocalConvert DXF units (mm, cm, m, inch, ft) — rescale the geometry, rewrite the $INSUNITS header, download a new DXF. Free, no upload, in your browser.
Drag files here, or click to browse
Supports DXF
Choose fileScales supported entities and rewrites the DXF. Supported: LINE/polyline/circle/arc/ellipse/point/text/solid. Other entity types (e.g. INSERT/SPLINE/DIMENSION/HATCH) are not converted — they are counted and reported in the result.
Irreversible scaling notice
All coordinates are globally rescaled (0.001× factor) with floating-point rounding; the original grid precision cannot be fully preserved. The output filename carries the target unit.
What is it? DXF Unit Converter changes the drawing units of a DXF (mm, cm, m, inch, foot) by scaling the supported entities consistently, so a drawing authored in one unit can be used in another.
TL;DR: Convert DXF units between mm, cm, m, inch and foot — geometry is rescaled and the $INSUNITS header rewritten, so real-world dimensions stay identical. Free, no upload, runs in your browser.
How to use
- Drop a .dxf file into the area — when the header declares $INSUNITS, the source unit is pre-filled from it (adjust if the drawing uses different units).
- Pick the source and target units.
- Click "Convert & download" — the rescaled DXF downloads (the filename carries the target unit).
FAQ
Is it a lossless conversion?
No — coordinates are scaled mathematically, but the rewrite is not bit-exact lossless: floating-point rounding applies; bulge arcs in polylines are flattened to straight segments; entity types outside the supported list are not carried over (counted per type in the result panel); entities with non-finite coordinates are skipped. Ellipses are rewritten as true ELLIPSE entities (start/end parameters preserved). See limitations.
Does it update the DXF header units?
Yes, the $INSUNITS header is rewritten to match the target unit.
Does it support binary DXF?
No — ASCII DXF only. Re-save the file as ASCII DXF in your CAD application and try again.
Which entities are rescaled?
Lines, polylines, circles, arcs, ellipses, points, text and solids. Other entity types such as INSERT, SPLINE, DIMENSION and HATCH are not converted and are counted per type in the result panel.
What are DXF units — does the file store them?
No. DXF coordinates are stored as plain numbers with no unit of their own; the $INSUNITS header in the HEADER section declares the unit the author intended. This tool pre-fills the source unit from $INSUNITS when the header is present, but the drawing is assumed to actually use the unit you select — the header alone is not used to judge the true units.
What is the difference between converting units and scaling the drawing?
Scaling multiplies every coordinate by a factor you choose, so the physical size of the drawing changes — use Transform DXF for scale, rotate, mirror and move. Unit conversion multiplies by the exact unit ratio (1 in = 25.4 mm) and rewrites the $INSUNITS header, so real-world dimensions stay identical and the drawing is simply expressed in different units.
Can I convert an inch DXF to mm for laser cutting or CNC?
Yes — pick inch as the source and mm as the target. Every supported entity is multiplied by 25.4, the $INSUNITS header is set to millimeters, and the downloaded filename carries the target unit so the shop floor gets the right file. Note the conversion is global floating-point scaling, so expect small rounding differences (see limitations).
Examples
- mm → inch: the whole drawing is rescaled by 1/25.4 and rewritten
Supported formats
Limitations
- Assumes the source drawing already uses the units you select.
- ASCII DXF only.
- Bulge arc segments in polylines (group code 42) are flattened to straight segments when the DXF is rewritten.
- Ellipses are rewritten as true ELLIPSE entities (dxf-writer drawEllipse); partial ellipses keep their start/end parameters (radians).
- Entities with non-finite coordinates (NaN/∞) are not converted and are counted as skipped in the result panel.
- Supported: line/polyline/circle/arc/ellipse/point/text/solid. Other entity types (e.g. INSERT/SPLINE/DIMENSION/HATCH) are not converted and are counted per type in the result panel.
- Scaling is global floating-point multiplication — small rounding differences are expected and the original grid precision is not fully preserved.
Privacy
Privacy first: this tool runs entirely in your browser — your input and files never leave your device, and everything is cleared when you close the page.