The formula behind any print price
Cost = price per kg × weight + print hours × hourly rate. Weight = volume × density × % solid. Each input comes from a different place:
| Input | Where it comes from |
|---|---|
| Volume, cm³ | the model; Info shows it after opening |
| Density, g/cm³ | the material, see the table below |
| % solid | walls, top and bottom layers and infill together |
| Price per kg | your spool or resin receipt |
| Print hours | your slicer, or the time from a G-code file |
| Hourly rate | your choice: power, wear, failed prints, your time |
This page sets out no market prices; you supply them, and the arithmetic stays the same.
Material: weight from volume and density
| Material | Density, g/cm³ | 20 mm cube, 8 cm³, solid |
|---|---|---|
| PLA | 1.24 | 9.92 g |
| PETG | 1.27 | 10.16 g |
| ABS | 1.04 | 8.32 g |
The same cube in ABS weighs 16 % less than in PLA, so a lighter plastic can offset a higher spool price. The Info panel holds 17 materials, from PLA to resins, aluminum, steel and titanium. The volume is only right on a closed mesh, so look at the watertight line in the mesh check before you trust it.
Infill: % solid is not the infill number
Walls, top skins and bottom skins print solid at any infill setting. On a small part those shells make up a large share of the volume, so 20 % infill can mean a part that is far more than 20 % solid. A large box at the same setting comes closer to 20 %. Treat the infill number as a lower bound.
The surest weight comes from the slicer itself. A G-code file states the filament used, and our reading of net extrusion was within 1.1 % of PrusaSlicer's number on 13 real files. The 3D printer filament calculator turns length into grams.
Machine time often outweighs the plastic
A part that uses a few grams can occupy the printer for hours. The hourly rate pays for electricity, nozzle and belt wear, the share of prints that fail and, for a business, the hours you spend at the machine. Print services also add setup, removing supports and finishing.
Take the hours from your slicer or from the G-code. Our 3D print time calculator replays the moves with acceleration: on 13 files it came out 0.6–8.8 % above PrusaSlicer's own estimate, median 2.6 %. From an STL sliced here the spread was −30 … +16 %. Nobody has timed a real print against it yet, so treat it as an estimate.
How much does 3D printing cost for one part: a worked example
The prices below are example inputs only. Replace them with your own spool price and rate.
| Step | Solid cube | Cube at 40 % solid |
|---|---|---|
| Volume | 8 cm³ | 8 cm³ |
| Weight in PLA (8 × 1.24 × % solid) | 9.92 g | 3.97 g |
| Material at an example 25 per kg | 0.25 | 0.10 |
| Time at an example 0.5 h × 1.00 per hour | 0.50 | 0.50 |
| Total, in your currency | 0.75 | 0.60 |
Even with these round inputs, time is the larger term. Lower infill saves plastic but changes the total less than a faster print would.
Pricing prints for other people
A quote built on a part that turns out 25.4 times too small, or on the volume of an open shell, is a loss you only notice after printing. Open the customer's file before you quote. Check the size in mm, the watertight line and the part count, since an open shell gives a wrong volume. The viewer flags Check the units when a part is longer than 2 m, weighs over 100 kg or the cost looks unrealistic. Then enter material, % solid, price per kg, hours and rate in the 3D print cost calculator and add your margin on top.
Questions and answers
How much does it cost to 3D print something small?
Weigh it first: an 8 cm³ PLA cube is 9.92 g solid. Multiply by your price per kg, then add print hours times your rate; the hours usually dominate.
How do I price 3D prints to sell?
Use the formula with your real spool price, a rate that covers power, wear and failures, then add labor for finishing and a margin.
What hourly rate should I use for my printer?
Set it from your own costs: electricity, spare parts, the share of failed prints and the value of your time. No single number fits every printer.
Does infill change the price much?
Less than people expect. Walls and skins stay solid, and on small parts machine time outweighs the saved plastic.
Where do I get the print time?
From your slicer or the G-code header. Our estimate from G-code ran 0.6–8.8 % above PrusaSlicer's on 13 files.
Why does the volume of my model look wrong?
Volume is only reliable on a closed mesh. If the mesh check says it is not watertight, run Edit → Repair first; if the size is 25.4 times off, the part was drawn in inches and Inches → mm fixes it.
Does the same formula work for resin printing?
Yes. Weight still equals volume × density × % solid, and the materials list includes resins. Hours come from your resin slicer, and the rate should cover resin waste and cleaning.