Tool · material cost

Will this print cost 20 grams or 400? Estimate before slicing.

One input — the print’s bounding box — and the estimator returns the PLA weight and cost at typical shell and infill settings. Good for the should-I-print-this-at-all decision.

Print size → material cost

Width (mm) Depth (mm) Height (mm) Price per kg

The assumptions, in the open

What the estimate assumes
Assumption	Value	When it moves
Shell + infill volume	≈ 22% of bounding box	A typical 2-wall, 15% infill print fills about a fifth of its box. Hollow decorative pieces drop near 10%; solid functional parts rise past 50%.
PLA density	1.24 g/cm³	Standard PLA. PETG is ~1.27, ABS ~1.04 — the weight scales with density if you switch.
Spool economics	1 kg / ~20 currency units	The per-gram figure defaults to 0.02; set your own from your spool price.

The biggest lever is the fill fraction. If you know your model is mostly air (a helmet, a vase, an open-frame prop), mentally halve the weight. If it is a solid mechanical bracket, double it.

Questions people ask

How accurate is estimating from the bounding box?

Within roughly ±30% for typical models, because the real variable is how much air the shape contains. A solid cube hits the estimate exactly; a lattice or an open wireframe uses far less. Treat the output as a budget line, not an invoice.

Why not slice it and read the exact weight?

Do that for the final print — the slicer is exact. The estimator exists for the decision before slicing: is this 30 cm statue worth 400 g of filament, and should it be 20 cm instead? One input, one answer, no slicer run.

Does converting 3MF to STL change the material cost?

No. The geometry is identical, so the printed volume is identical. Cost depends on the size you print at and your slicer’s shell and infill settings — the format of the file you fed in is irrelevant.

What about supports and failures?

Add their cost mentally: supports commonly add 10–25% for figures with overhangs, and a failed print costs the whole job. The estimator covers the model alone — multiply by 1.2 for a supported print, and keep a spool’s worth of margin for the one that teaches you something.

Resin instead of filament?

The volume estimate carries over, but resin is sold by volume (litres) and printed parts are usually hollowed. Divide the printed volume by your hollowing shell thickness logic — different math, same bounding-box starting point.

Next: convert the 3MF to STL, then read what each format carries before you archive either.

Why the bounding box is a budget, not a quote

The estimator multiplies the model's bounding box by a typical fill fraction, then applies the material density and your spool price. That is enough to answer “is this print worth starting?”, not “what will the slicer say?”. The real number depends on walls, infill, supports, purge and the actual shape inside the box.

A hollow vase and a solid bracket can share the same bounding box and differ by a factor of five in material. The estimate deliberately sits in the middle; treat it as a planning number with a wide error bar.

The three levers that move the estimate most

Print size. Material scales roughly with the cube of a uniform scale change, so a 20% larger print is far more than 20% heavier.
Walls and infill. A 15% infill with two walls is the default assumption; a solid part can double or triple the estimate.
Spool price. The per-gram cost changes the currency answer, not the weight. Update it when the spool changes.

When to stop estimating and slice

Once the decision is “yes, print it”, slice the model and read the exact filament figure. The estimator is for the earlier decision: whether the size, material and time are worth committing to at all.

A note on supports and failures

Supports add material and time, and a failed print costs the whole job. If the model has steep overhangs or a tall, narrow shape, add a margin to the estimate rather than treating it as a ceiling. Then slice the model and read the exact figure.

What moves the estimate

Four levers explain most of the gap between the estimate and the slicer.

Estimate levers
Lever	Direction	Why
Print size	Cubic	Volume scales with the cube of a uniform change
Walls and infill	Up	More plastic inside the same box
Supports	Up	Extra material for overhangs
Spool price	Currency only	Weight stays the same

If the estimate is far outside the budget, resize the model before slicing; a smaller print is cheaper than a failed one.

A failed print costs the whole job, not just the part; keep a margin.