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

Wall Thickness Checker

Drop a 3D model and pick your print process. Every face is measured to the opposite wall and painted red when it is thinner than your minimum, yellow when it is close and green when it is fine. You get the thinnest wall, the median, the share of thin surface and a list of thin areas.

Loading the wall thickness checker...

How to check wall thickness

  1. 1

    Drop your model

    Drag an STL, OBJ, 3MF or GLB onto the checker, or press Choose file. It is read and measured in your browser; nothing is uploaded.

  2. 2

    Pick your process

    Choose FDM, resin or SLS for a typical minimum wall, or type the value your printer or print service asks for.

  3. 3

    Read the heatmap

    Red faces are thinner than your minimum, yellow ones are close, green ones are fine. Press Focus on a thin area to fly the camera to it.

  4. 4

    Fix and check again

    Thicken the red parts in your 3D app, scale the model up, or make a sturdier version with AI, then drop the new file in to check it.

Minimum wall thickness by process

The presets are typical starting points taken from printer and print-service design guides. They are not guarantees: the real limit depends on your printer, material, settings and how big the wall is.

FDM, 0.4 mm nozzle: 1.0 mmAbout two lines of a 0.4 mm nozzle. One line (about 0.45 mm) is the bare minimum a slicer can print; 1.2 mm or more is sturdier for parts that take load.
Resin (SLA / MSLA): 0.6 mmFor walls that stand on their own. Walls held by the rest of the part on both sides can often go thinner, about 0.4 mm.
SLS nylon powder: 0.6 mmFor upright walls. Flat, horizontal walls can be thinner, but very thin walls can warp or break when the powder is cleaned off.
CustomYour printer or print service lists the minimum it accepts in its design guide. Type that value; it can depend on the material and on the size of the wall.

What the colours mean

Each face is coloured by the thickness measured behind it, compared with the minimum you chose.

RedThinner than the minimum you set. These walls may not print, may print with gaps, or may break.
YellowBetween the minimum and 1.5 times the minimum. They will usually print, but check them.
GreenAt least 1.5 times the minimum.
GreyNot measured: the face has no wall behind it, which means the mesh is open (has holes) there.

Too thin? Regenerate a sturdier model with AI

Turn a photo into a new 3D model and check its walls here before you print. The AI generator uses credits; this checker does not. If the size of your part is not fixed, scaling it up also makes every wall thicker.

Image to 3D with AI →Scale up to fix thin wallsClose holes first

More free 3D printing tools

STL repairScale STLSTL viewer3D print cost calculatorImage to STL with AICompare STL files

Wall thickness checker FAQ

Drop the STL onto the checker at the top of this page and pick your print process (or type a minimum wall). After a few seconds every face is coloured: red is too thin, yellow is close, green is fine. The panel shows the thinnest wall, the median and a list of thin areas you can focus on.
It depends on the process, the material and the size of the part. Typical starting points from printer and print-service design guides are about 1 mm for FDM with a 0.4 mm nozzle (two lines), about 0.6 mm for resin walls that stand on their own and about 0.6 mm for upright SLS nylon walls. Always check your printer's or service's own guide; these are not guarantees.
From the middle of each face a ray goes straight into the part until it leaves the part on the other side. From the middle of that ray, four more measurements go across the wall in different directions, and the shortest one is the thickness. This finds thin fins, thin edges and thin shells. It is an estimate, like other ray-based checkers, not a full simulation of your slicer.
Grey faces have no wall behind them, so nothing could be measured. That happens when the mesh has holes or is a single surface with no thickness at all. The numbers are then approximate. Close the holes first, for example with the free STL repair tool, and check again.
STL and OBJ files do not store units. The checker assumes millimetres. If your model was made in centimetres, inches or metres, change Model units and all the numbers and colours update. The size of the model is shown in the panel so you can see if it is right.
Thicken them in your 3D app (shell or offset the surface), scale the whole model up if its size is not fixed, choose a process that prints thinner walls, or make a sturdier version with the AI image-to-3D generator and check it again here.
STL (binary and ASCII), OBJ, 3MF and GLB up to 100 MB and 1.5 million triangles. Several parts in one file are measured together. Small models with few triangles are split into smaller faces first so the heatmap shows detail.
No. The file is read and measured in your browser, in a background worker, and never leaves your device. You can download the heatmap as a PNG report or as a coloured GLB.

Thickness is a ray-cast estimate made in your browser. Minimum-wall values are typical starting points, not guarantees; always check the design guide of your printer or print service.