3D Print Cost Calculator: filament weight and price from your STL

A print's material use comes down to one question: how much of the model's volume is actually plastic. This 3D print cost calculator starts from the true volume of the mesh (computed from the triangles, so the STL must be watertight for the number to mean anything) and splits it in two. A share of it, the wall factor, is treated as solid: the outer walls, the top and bottom layers, any thin features that are all wall. The rest is interior and gets multiplied by the infill percentage. The sum is the plastic volume, which times the density of the material gives grams, which times your price per kilogram gives cost.

In symbols: plastic = V x (wall + (1 - wall) x infill), grams = plastic x density, cost = grams / 1000 x price per kg. The density presets are PLA 1.24, PETG 1.27, ABS 1.04, TPU 1.21 and resin 1.10 g/cm3, and you can type any other value. Price defaults are editable; put in what you actually paid for the spool.

Like every tool on this site, the work happens in your browser. The file is read from your device, parsed in memory and drawn with WebGL; no copy is sent anywhere. Open the network panel of your browser's developer tools while you load a model and you will see no upload. Close the tab and the model is gone.

Drop a 40 mm cube. Its volume is 40 x 40 x 40 = 64,000 mm3, or 64.00 cm3, and it is watertight, so the estimate is valid. Set wall factor to 15 percent, infill to 20 percent, material to PLA and price to 22 per kg.

Volume           64.00 cm3
Solid share      15 %  ->  9.60 cm3
Interior         85 %  ->  54.40 cm3 x 20 % infill = 10.88 cm3
Plastic volume   20.48 cm3
PLA 1.24 g/cm3   25.4 g
Cost at 22 /kg   0.56

Twenty-five grams and a little over half a unit of currency. For reference, 20.48 cm3 of 1.75 mm filament (cross-section 2.405 mm2) is about 8.5 metres off the spool. Switch the preset to PETG and the same volume weighs 26.0 g; to ABS, 21.3 g. Change infill to 100 percent and the cube is 64 cm3 of plastic, 79.4 g of PLA, which is what a solid calibration cube would cost you.

Now the honest part. A slicer will not give you 25.4 g exactly. PrusaSlicer with two 0.45 mm perimeters, five top and bottom layers at 0.2 mm and 20 percent gyroid infill reports around 25 to 29 g for this cube, because its wall volume depends on the actual perimeter count and layer height, its infill pattern has its own density curve, and it adds skirt, brim or purge lines. The 15 percent wall factor is a reasonable stand-in for a mid-sized solid part; a thin-walled vase is closer to 100 percent wall and a large box closer to 5 percent. Use this page to compare designs, quote a rough price or choose a material; use the slicer for the number you will actually put on an invoice.

• Estimates, not quotes. Slicers compute from real toolpaths and differ by 10 to 20 percent from this simple model; supports, brims, rafts and purge are not included.
• Needs a watertight mesh. Open or self-intersecting meshes produce a wrong volume; the page warns, and STL repair shows what is wrong.
• Units: STL has none. If the model is 1.575 mm wide because it was exported in inches, the cost will be 16,000 times too low. Check the dimensions first.
• Print time, electricity, machine wear and labour are not estimated. Material is usually the smallest part of a commercial quote.
• Multi-material and multi-colour prints are treated as one material.