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3DAI
Free · runs in your browser · files stay on your device

STL Splitter

Drop a model that is too big for your 3D printer and pick your bed size. The splitter finds the fewest cuts so every part fits, adds dowel holes or pegs so the parts line up, and lays each part flat. Download numbered STLs or one ZIP. It all runs in your browser.

Loading the STL splitter...

How to split an STL to fit your bed

  1. 1

    Open the model

    Drop an STL, 3MF, OBJ or GLB file, or try the sample. Check the size; change the file units or scale it to a height if it looks wrong.

  2. 2

    Pick your bed

    Choose a bed size or type your own X, Y and Z, and keep a safety margin (5 mm by default) so parts do not touch the edge.

  3. 3

    Choose connectors

    Dowel holes with printed pins, pegs printed on one half, or plain flat cuts for glue. The plan shows how many parts you get.

  4. 4

    Split and download

    Press Split. Check that every part says it fits, pull them apart with the Explode slider, then download the ZIP and print.

Dowels, pegs or flat cuts

Connectors are placed only where the cut face is solid, with a wall around each hole, so they never break through the surface of the model.

ConnectorWhat you getBest for
Dowel holesA round hole in both halves of every cut, and pins.stl with one pin per pair of holes.Strong joints and easy lining up; pins print upright and fast.
PegsA peg printed on one half and a matching hole in the other.No loose pins to lose; the part with pegs never lies on the peg side.
NoneFlat cut faces only.Glue joints, very thin walls, or when you add your own joints in CAD.

Settings and defaults

The defaults suit most desktop printers. Every value can be changed before you split.

SettingWhat it doesDefault
Safety marginSpace kept free on every side of the bed and at the top.5 mm
Turn partsLets a part lie on its side when that saves a cut.Off
Lay flatPuts each part on its biggest flat side, usually the cut face.On
DiameterHole size for dowels and pegs.5 mm
Depth / lengthHow deep each hole goes into each half (or how far a peg sticks out). Shortened on thin parts.8 mm
ClearanceHow much thinner a pin or peg is than its hole.0.15 mm

Make a big print from a photo

Turn a photo into a 3D model with AI, scale it up as big as you like, then split it here to print it in parts. The AI generator uses credits; this splitter does not.

Photo to 3D model with AI →Scale an STLRepair an STLImage to STL

More free 3D printing tools

Scale STLSTL repairSTL viewerReduce STL file sizeImage to STL3D print cost calculator

STL splitter FAQ

Open the file at the top of this page, choose your print bed size and press Split. The tool cuts the model into the fewest parts that fit inside the bed minus the safety margin, and you download each part as its own STL or all of them in one ZIP. No signup and no install.
It compares the model size with the usable bed space and tries every grid of cuts along X, Y and Z, keeping the one with the fewest parts where every part fits. Cuts are spaced evenly, so the parts come out about the same size. If you allow turning, a part may also lie on its side when that saves a cut.
Yes. Turn on Manual cuts to set how many parts you want along each axis and drag each cut plane, or type its position in millimetres. The plan warns you when a part is still too big for the bed.
Dowel holes put a hole in both halves and give you a separate STL of pins, which print quickly and give strong joints. Pegs are printed on one half, so there are no loose parts, but that half cannot lie on the peg side. Connectors are only placed where the cut face is solid enough for them, never through a thin wall.
The default is 0.15 mm, a slip fit that leaves room for glue; around 0.10 mm gives a tight press fit. Printers differ, so if pins are too tight or loose, print one test pair and change the clearance.
No. The file is read and cut on your device, in your browser. The only thing the page downloads is the open-source geometry engine that does the cutting. Your model never leaves your computer.
The cut faces can only be filled when the mesh is watertight, with no holes or loose edges. For other meshes the tool still makes a best-effort cut, but the parts stay open and have no connectors. Repair the file with the free STL repair tool first, then split it again for closed parts.
STL (binary and text), 3MF, OBJ and GLB, up to 100 MB and 1.5 million triangles. STL, OBJ and 3MF are read as millimetres and GLB as metres; you can switch the units to mm, cm, m or inches, flip Y-up files to Z-up, or scale the model to a height before you cut.