Look at the model, not the camera
X, Y and Z refer to the file’s stored orientation. Turning the view does not rotate the geometry. Compare the axis directions with the model’s features before deciding which plane would create a useful joining face.
ONE MIDPOINT PLANE, TWO SIDES TO CHECK
Cut STL in half.
Choose X, Y or Z.
Cut STL in half when a centered seam suits the model. Choose an axis and the tool calculates the midpoint from its bounds, then creates capped pieces on either side. Your file is read on this device, without an upload step.
Real, capped geometry 100% local file processing Free to use, no sign-up
LOCAL WORKSPACE Your files stay on your device
01
Your model
.STL02
Split settings
No upload. No account. No installation.
ROOM FOR YOUR NEXT BIG IDEA
Add a model to make it fit.
XYZmm
Drag to rotate · Scroll / pinch to zoom
Waiting for a modelScale 1:1 · mm
All cuts run on your device
Half-length is measured in source coordinates, read as millimeters, without changing scale.
A CENTERED CUT WITHOUT ENTERING COORDINATES
Choose an axis to cut STL in half
Compare the midpoint planes
To cut STL in half from left to right in model coordinates, choose X; front to back uses Y, and upper to lower uses Z. The displayed plane changes immediately, letting you inspect whether it crosses thin walls or important details.
Generate and inspect both pieces
Run Cut in half, explode the result and highlight each side. Save two individual STLs or the ZIP. If you change axes after reviewing the result, run the operation again so the downloads reflect the new choice.
AXIS CHOICE CHANGES THE RESULTING DIMENSIONS
Cut STL in half where the two sections will be useful
For a rectangular 120 × 80 × 200 mm model, an X cut makes two 60 × 80 × 200 mm sections. A Y cut makes two 120 × 40 × 200 mm sections; a Z cut makes two 120 × 80 × 100 mm sections. If the height is your printer’s limiting dimension, Z is the relevant starting point. If a visible seam or fragile attachment matters more, inspect another axis. To cut a STL file in half through a symmetric centerline, check that the intended symmetry actually matches the bounding-box midpoint. A protruding handle can move that midpoint away from the main body’s center.
After you cut STL in half, open both files in your slicer and check their dimensions against the usable build volume. Orient each independently, lower it onto the bed and inspect the layers near its new cap. Midpoint mode does not check a printer preset, so either half may still be too wide, deep or tall.
Move a seam off-center with the manual STL cutting tool.
If either half remains oversized, try the STL splitter’s printer-fit mode.
For more sections, divide the model with a part grid.
Split model in half for printing: choose a footprint
To split a model in half for printing, consider whether the seam gives each piece a broad bed contact area. A flat cut through a thin shell leaves only a narrow rim. That may need a brim or a different orientation to stay attached.
Cut 3D model in half while protecting walls and details
When you cut a 3D model in half, look for small islands near the plane and features that would become unsupported. The cap seals solid wall cross-sections; a hollow model’s internal cavity stays empty. It does not create internal support structures.
Understand what half means
If Z bounds run from −30 to 170 mm, the midpoint is 70 mm: (−30 + 170) / 2. Both spans measure 100 mm. An asymmetric solid can still have different material volumes and print times on the two sides; this is not a balancing calculation.
Plan the join before slicing
You can cut STL in half and glue the flat mating faces, but the exports contain no alignment pins, sockets or magnet holes. Check how the surfaces register, choose adhesive for the filament and design extra locating features yourself if the assembly needs them.
FOUR WAYS TO START
A different cut for a different job.
STL splitter
Divide by your printer’s build volume.
STL cutter
Place one precise axis-aligned cut.
Split STL into parts
Choose an equal-width grid of parts.
Cut in half
Split at the center on X, Y or Z.
MIDPOINT RESULTS AND PRINT PREPARATION
Questions before you cut STL in half
Find the current tool boundaries and learn about browser file privacy.
Can I split STL in half through a particular socket?+
Only if that socket lies on the selected midpoint plane. For an exact location, use the manual cutter and enter its coordinate. The centered mode cannot move the seam while keeping the selected axis unchanged.
What should I check before printing the second half?+
Check it separately even if the first piece slices cleanly. The opposite side may have a different overhang, thin feature or smaller contact patch. Review supports and orientation for both objects, and dry-fit the printed faces before final assembly.
Can I cut STL in two if it contains open surfaces?+
The input must describe a closed solid. Repair gaps and non-manifold edges before retrying. A surface that looks closed in the viewer may still have invalid topology; use the reported error rather than judging the shaded preview alone.
Do I need an account to cut STL in half and save it?+
No. Select a file, make the centered cut and download the pieces without registration or payment. Keep a local copy of each output before closing the tab; the workspace is not a saved project library.