A spaghetti print at hour six of an eight-hour job still burned filament, electricity, and printer hours before it was scrapped. The failed part itself is thrown away and forgotten -- but its cost is not. It moves onto the price of the print that actually sells, because on average it takes more than one attempt to land one sellable part.
Below is the same print, priced twice, with nothing changed except the failure rate: 45g of filament at $22/kg, a 3-hour print on a $250 printer amortized over 3000 hours, 10 minutes of post-processing at $20/hr, $0.75 packaging, an 8.5% marketplace fee, and a 35% target margin.
| Failure rate | 5% | 25% |
|---|---|---|
| Attempts needed per sellable part | 1.05 | 1.33 |
| Failure buffer added to the part's cost | $0.07 | $0.43 |
| Total cost per sellable part | $5.45 | $5.81 |
| Break-even price | $5.96 | $6.35 |
| Suggested price (35% margin after fee) | $9.64 | $10.29 |
Same filament weight, same print time, same printer, same labor and packaging -- the only input that moved is the failure rate, and it alone is worth $0.64 on the price you would need to charge to hold the same margin. That $0.64 is invisible in a per-print filament receipt, because the receipt is for the print that sold, not for the one that got scrapped an hour earlier.
It is applied only to the costs that a failed attempt still spends before it is scrapped: material, electricity, and the printer's own amortized wear. Post-processing time and packaging are not inflated by the failure rate, because a failed attempt is scrapped before it ever reaches the finishing bench -- only the successful part gets sanded, assembled, and boxed.
Not the cost of the failed print itself -- that filament and time is already gone the moment the part is scrapped. What it costs you is a buffer added to the price of the print that succeeds, because on average it takes more than one attempt to land one sellable part. On an otherwise identical print, moving the failure rate from 5% to 25% raises that buffer from about $0.07 to about $0.43 per successful part, and raises the price you would need to charge (to hold the same margin) by about $0.64.
Because a failed attempt still spent filament, electricity, and printer wear before it was scrapped, and that spend has to be recovered from somewhere -- there is no failed-print customer to bill it to. If 1 in 4 attempts fails, landing one sellable part takes on average 1 / (1 - 0.25) = 1.33 attempts, so the material, electricity, and machine-wear cost of a single attempt gets multiplied by 1.33 before it is charged to the part that actually sells. Post-processing time and packaging are not inflated the same way, because those only ever touch the part that succeeded.
Yes, and it is easy to miss because the failed part itself is thrown away and forgotten, while its cost quietly moves onto the next attempt's price. Two prints that are identical in every other input -- same filament weight, same print time, same printer, same labor and packaging -- price differently once their failure rates differ, because the failure-rate multiplier is applied to material, electricity, and depreciation before anything else is added.
On the worked example on this page (45g filament at $22/kg, a 3-hour print, a $250 printer amortized over 3000 hours), the failure buffer alone drops from about $0.43 to about $0.07 per successful part -- roughly $0.36 saved on every part you sell, before even touching labor or packaging. Across a run of 50 parts a month that is about $18, entirely from bed adhesion, supports, and calibration rather than from filament or fees.
Price your own printThis calculator needs no account and no upload: it is a static page, the arithmetic runs in your browser, and the figures you type stay on this device.