Material
Usually 1000g (1kg) or 500g — check the spool label.
Material cost
$1.00
- Filament used
- 50 g
- Cost per gram
- $0.02
How it's calculated
Filament is sold by weight, so the material cost of a print is a simple proportion of a spool's price:
Cost per gram
Spool price ÷ Spool weight
Material cost
Cost per gram × Filament used
The spool weight should be the net filament weight printed on the label (almost always 1000g, sometimes 500g or 750g) — not the weight of the spool with the plastic reel included.
Assumptions
- Your inputFilament used, spool price, and spool weight — you enter these directly.
- Derived valueCost per gram and total cost are derived exactly from the inputs above — there's no approximation in this calculation.
Worked example
A 1kg (1000g) spool of PLA costs $20. Your slicer says a model uses 84g of filament.
Cost per gram: $20 ÷ 1000g = $0.02/g. Material cost: $0.02/g × 84g = $1.68.
Frequently asked questions
Where do I find how many grams a print used?
Your slicer (PrusaSlicer, Cura, Bambu Studio, OrcaSlicer, etc.) estimates filament weight for the loaded model before you print — look for it in the print preview or export summary. For a print already in progress or finished, you can also weigh the spool before and after and take the difference.
Does this account for wasted filament from failed prints?
Not directly — this calculator assumes the grams you enter is what a successful print consumes. If you want to spread the cost of occasional failures across your prints, use the failure allowance field on the 3D Printing Cost Calculator instead.
What if I only know the price per kilogram, not per spool?
Enter 1000 as the spool weight in grams and your price per kilogram as the spool price — the cost-per-gram math comes out the same either way.
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