// Free tool · 3D printed helmets

Helmet size calculator

To scale a 3D printed helmet to your head, compare your head's width and length, plus room for padding, with the helmet's inside size at 100 percent, and scale it by the larger ratio. Enter your numbers below: the calculator gives the scale percentage for your slicer, the helmet's finished size, and whether it fits your printer in one piece. The fields start on example values.

Your head Units Head width ear to ear, just above the ears Head length forehead to the back of the head Room for padding on each side; measure the padding you'll use

The helmet file at 100% Outside width from your slicer's size box Outside length front to back Outside height Shell thickness wall thickness of the helmet itself

Your printer Printer

Build volumes are the makers' published figures, in millimetres.

Scale in your slicer

Finished outside size
Inside room, width
Inside room, length
On your printer

How to get a helmet that fits

Measure twice. Width just above the ears, length from forehead to the back of the head, using two books or boxes flat against your head and a ruler between them.
Leave room for padding. Measure the foam you plan to use and put its thickness in the padding box. Comfort pads compress a little, a hard shell doesn't.
Scale evenly. Use the one percentage above for X, Y and Z so the helmet keeps its shape. Stretching one axis makes it look wrong from the side.
Print a test ring. In the slicer, print only the bottom 15 to 20 mm of the helmet at your scale. It takes little filament and tells you if it goes over your head and sits right.
Split it if it doesn't fit. Cut the helmet along its panel lines so each part fits the printer; the seams disappear once they're filled and sanded.

Next steps: what the print will cost in filament and power, the printer size guide, and the guide to finishing 3D printed props. The Star Wars, Marvel, Halo and Helldivers 2 print libraries hold the most helmet files on PropBuilds.

Helmet sizing questions

How do you scale a 3D printed helmet to fit?

Measure your head's width and length, add room for padding on each side, and compare that with the helmet's inside size at 100 percent. Scale the whole helmet by the larger of the two ratios, the same in every direction, so it keeps its shape. Then print only the bottom ring of the helmet at that scale and try it on before you print the rest.

How do you measure your head for a helmet?

Stand two books or boxes flat against the sides of your head, just above the ears, and measure the gap between them: that's the width. Do the same from your forehead to the back of your head for the length. A friend and a tape measure make it easier, and measuring twice is worth it.

How do you find a helmet file's size?

Load it in your slicer at 100 percent and read the size box, usually shown as X, Y and Z. The helmet's width and length are the two horizontal sizes when it sits upright. The inside is smaller by the shell thickness on each side, which you can measure in the slicer's section view.

Can you scale 3D printed armor the same way?

Yes. Measure the body part the piece covers, add room for padding or clothing underneath, compare it with the part's inside size at 100 percent, and scale by the larger ratio. Test with a thin slice before printing a whole plate.

What size printer do I need for a helmet?

It depends on the helmet at your scale: this calculator checks each printer's build volume against the scaled helmet. If it doesn't fit in one piece, split it into parts along panel lines; most slicers can cut a model.

Results are estimates from the numbers you enter; a test print is the real check. Your numbers stay in this browser.