Filament cost per print.

To find the filament cost of a 3D print, you need two reliable numbers: the amount paid for the spool and the total material weight estimated by your slicer. The formula works for PLA, PETG, ABS, TPU, and other filaments sold by net weight.

The cost-per-gram formula

Use the net filament weight printed on the package. Do not divide by the physical weight of filament plus the empty spool, box, or reusable deposit.

Illustrative cost per gram by material

These prices are example inputs, not market averages. Replace them with the amount on your receipt.

Worked example: a 185 g print

Assume a slicer estimates 185 g and the seller adds a 7% material-waste allowance. With the illustrative $22.99 PLA spool:

The same 185 g slicer input would produce the following material-only estimates:

This comparison isolates spool price. It does not mean the same model will always consume 185 g in every material. Density, extrusion settings, support strategy, walls, infill, and the material profile can change both weight and duration. Reslice with the actual production profile.

Which slicer number should you use?

Use total filament consumed, not only the material remaining in the finished object. Depending on the job, that can include:

• the model, supports, brim, raft, or skirt
• prime towers and flushed or purged filament
• material used during color changes

This matters most in multicolor jobs, where the finished object can weigh far less than total spool consumption. When the slicer provides both length and weight, grams are usually simpler for business calculations because spools are sold by net weight.

How much waste allowance should you add?

There is no honest universal percentage. A tuned, single-color PLA job may produce little routine waste; a multicolor job or difficult material may produce much more. Track slicer grams, actual spool consumption, purge, support material, damaged stock, and partial remnants by product family.

Keep routine material waste separate from failed-print risk when possible:

If affected cost is $10 and the recorded failure rate is 10%, the adjusted amount is $10 ÷ 0.90 = $11.11. Simply adding 10% gives $11.00 and slightly understates the long-run cost of one failure in every ten attempts.

Material changes more than spool cost

PLA

PLA is generally straightforward to print and tends to warp less than many alternatives, which can reduce setup and failure cost for suitable products. It is not the right choice for every temperature, UV, or mechanical requirement. See the Prusa PLA guide for an official material overview.

PETG

PETG can be useful for durable functional parts, but stringing, bridging, and support removal can increase cleanup time depending on geometry and profile. Price that labor, not only the extra cents of filament. See the Prusa PETG guide.

ABS

ABS may require enclosure, ventilation, and additional attention to warping. Those requirements can affect equipment, energy, failure risk, and workspace cost. See the Prusa ABS guide.

TPU and flexible materials

Flexible materials may print more slowly and require more careful loading, support, and cleanup. Machine time and labor can matter more than the spool-price difference. See the Prusa flexible-material guide.

Five common material-cost mistakes

1. Using spool price as the complete job cost.
2. Ignoring support, brim, and purge material.
3. Using finished-model weight instead of total slicer consumption.
4. Reusing one gram estimate across materials without reslicing.
5. Forgetting that moisture damage, partial spools, and failed jobs reduce usable inventory.

Material is only one line in a sustainable price. Add machine time, electricity, labor, packaging, shipping, selling fees, licenses, and a profit target before quoting a customer.