Use the STL Overhang & Support Checker
Colour an STL by overhang: see which faces exceed your slicer's overhang angle, how much of the surface needs support, and an estimate of support volume.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
A bracket lying flat has 0% support and 18 cm² on the bed; stood on end the same bracket shows 24% of its surface in red and about 6 cm³ of support. Flat wins.Open the STL Overhang & Support Checker
Illustration. Open the tool for the real thing.
What is the STL Overhang & Support Checker?
Overhangs are the main reason FDM prints fail or need support material. This tool classifies every triangle of your model: red faces are overhanging more than your chosen angle from vertical and are not resting on the bed, green faces print fine without support, and blue faces are flat on the bed. Drag the angle slider (most slicers default to 45–50°) and watch the colours change live.
From that classification it reports the percentage of surface area needing support, the overhang area, bed-contact area and an estimate of support volume and weight — computed by casting each overhang straight down onto the first surface beneath it on a height grid. Try rotating the model by 90° or flipping it to compare orientations instantly, or jump to the automatic orientation optimiser.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Red / green / blue faces recalculated as you move the angle slider.
Overhang area, support volume (cm³) and weight for your material and density.
Rotate 90° or flip and re-evaluate in one click.
Percentages are computed face by face from the real mesh.
AZRS tools are free to open and use.
It opens in your browser, so there is nothing to download.
Used for
Pick one to see how it fits.
Designers
Spot overhangs that could be redesigned with chamfers instead of supports.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This 3d tool | Desktop software | |
|---|---|---|
| Install | Nothing to install | Usually an app or program to install |
| Account | No signup | Depends on the product |
| Cost | Free to use | Free or paid, depends on the product |
| Where it runs | In your browser tab | On your computer |
Questions people ask
How is the overhang angle defined?
From vertical: 0° is a vertical wall, 90° is a flat ceiling. A 45° threshold flags faces tilted more than 45° outward-and-down.
How accurate is the support volume?
It is an estimate (±30% typical) from straight-down columns; real support styles vary.
Why are bottom faces blue not red?
Faces lying on the bed need no support and add stability.
Is it private?
Yes, all processing happens locally.
How do I use the STL Overhang & Support Checker?
1. Drop in your model. 2. Set the overhang angle your slicer uses. 3. Rotate or flip to try other orientations. 4. Read the support percentage and estimated material.
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Try the STL Overhang & Support Checker now
See which faces need supports at your slicer's overhang angle. Free to use.
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