Around $5.15, for 100 g of PLA at $22/kg on a machine drawing 100 W over an 8-hour print, with an 8% failure allowance and 30 cents an hour of machine time.
The plastic is $2.20 of that. Most people stop counting there, which is why quoted prices for print work tend to come in at less than half of what the job really costs.
The four terms, smallest sensitivity first
- Electricity — $0.14. 0.8 kWh at 17.5 cents. Even tripling the wattage or doubling the rate leaves this the smallest line on the page.
- Filament — $2.20. Directly proportional to spool price and to the grams the slicer reports. The grams figure is the one worth checking: if your filament profile still carries PLA's 1.24 g/cm³ while a denser blend is loaded, this term is wrong by exactly the density ratio.
- Failure allowance — $0.41. An 8% failure rate is not an 8% surcharge. It means 1.087 attempts per finished part, because the attempt you scrap has to be paid for out of the ones you keep.
- Machine time — $2.40. The largest single lever here, and it is nothing to do with the part. It is 8 hours multiplied by whatever you decide an hour of your printer is worth.
Why the hours matter more than the grams
Two of the four terms are billed by time, not by mass. A 100 g part that prints in 8 hours and a 100 g part that prints in 3 carry identical filament costs and very different totals.
That is worth remembering when you are deciding between a tall thin part at 0.15 mm layers and the same geometry at 0.28 mm. The mass is unchanged; the bill is not.
If you print for other people
Add labour. Slicing, plate prep, removal, support cleanup and packing are hands-on minutes that do not appear anywhere above, and on a small part they are frequently the largest term of all — twenty minutes of your time at any plausible rate exceeds the $5.15 this part costs to make.
Rerun it with your numbers
The two inputs worth changing first are your real spool price and your own hourly machine allowance. Both are in the print cost calculator. If you are pricing work rather than curious about it, the resale pricing guide covers margin against markup, which is where most quoted figures actually go wrong.