Purge waste costs the price of the filament you throw away. On our test model, a single-nozzle printer used 1,079 g of filament outside the model and Quadro used 135 g. At an example price of $20 per kilogram, that's about $21.58 versus $2.70 per print, a difference of $18.88.
Filament is cheap per gram, so waste is easy to ignore. Over many prints, it isn't. Here's the formula, our numbers and what they look like over a year.
The Formula
Waste cost per print = waste in kilograms × price per kilogramWaste is the filament used outside the model: purge towers, flushed filament and discarded strands. You can measure it by weighing the leftovers, or by subtracting the model's weight from your slicer's total filament estimate. We walk through it in How Much Filament Does Multicolor Printing Actually Waste?.
Our Test Numbers
On the same multicolor model, we measured the filament used outside the model:
| Single-nozzle printer | Quadro | |
|---|---|---|
| Filament used outside the model | 1,079 g | 135 g |
| Cost at $20 per kg (example price) | $21.58 | $2.70 |
The difference is 944 g, or $18.88 per print at the example price. Use your own filament price in the formula for your own number.
Per Year: Three Example Scenarios
These assume every print wastes the same amount as our test model. Real prints vary, so treat the numbers as an illustration, not a forecast.
| Prints per year | Single-nozzle cost | Quadro cost | Difference |
|---|---|---|---|
| 10 | $215.80 | $27.00 | $188.80 |
| 50 | $1,079.00 | $135.00 | $944.00 |
| 200 | $4,316.00 | $540.00 | $3,776.00 |
At $20 per kg, 50 prints of this kind add up to about $944 in filament that never ends up in a model.
What the Numbers Don't Show
- Your model matters. Waste depends on the number of color changes, color contrast and settings. A model with few changes wastes much less. See Purge Towers Explained.
- Quadro isn't zero. A small priming extrusion remains, which is the $2.70 in the table. See Why Quadro Doesn't Purge.
- Time and effort. Emptying purge bins, cutting up purge towers and dealing with the pile are costs too, though they're harder to price.
- Filament price. Specialty materials cost more per kilogram, which raises the cost of every wasted gram.
How to Work Out Your Own Number
- Pick a typical multicolor print.
- Read the slicer's total filament estimate, and the model's own weight.
- Subtract: that's your waste in grams.
- Divide by 1,000 and multiply by your filament price per kilogram.
- Multiply by the number of similar prints you make in a year.
Key Takeaways
- Waste cost is the weight of discarded filament times its price.
- On our test model, the difference was 944 g per print, about $18.88 at $20 per kg.
- Costs grow with the number of multicolor prints and the number of color changes.
- Measure your own model before drawing conclusions.
For a broader comparison of printer designs, including how each handles color changes, see our multi toolhead 3D printer buying guide and AMS vs Tool Changer.
Curious how much you'd save? See Quadro or visit the Kickstarter page.
3. FAQ
How much does multicolor purge waste cost? It equals the weight of the discarded filament times its price per kilogram. On our test model, a single-nozzle printer wasted 1,079 g, about $21.58 at $20 per kg, versus 135 g or $2.70 on Quadro.
How do I calculate my own filament waste cost? Subtract the model's weight from the slicer's total filament estimate to get the waste in grams, divide by 1,000 and multiply by your price per kilogram.
Does purge waste cost more with specialty filaments? Yes. The waste weight is the same, but a higher price per kilogram makes each wasted gram more expensive.
Does Quadro waste any filament? A small amount. Quadro doesn't purge to clear one color from a shared nozzle, but it uses a small priming extrusion to stabilize pressure when a toolhead resumes.
Do these numbers apply to every print? No. They come from one multicolor model. Waste depends on the number of color changes, color contrast and slicer settings.
