About 15 g in PLA, at 0.2 mm layers with a normal two-wall profile. That is 12.1 cm³ of plastic and 5.03 m of 1.75 mm filament.
The figure is quoted so often because the model is fixed: 60 mm long, 31 mm wide, 48 mm tall, and identical on every machine that prints it. What is not fixed is the profile.
What moves it, and by how much
- Layer height. A Benchy at 0.1 mm uses very nearly the same mass as one at 0.2 mm, because the volume of the hull is unchanged. It takes twice as long, and this is the single most common misunderstanding about layer height.
- Wall count. This does change the mass. A Benchy is mostly shell, so going from two walls to four adds material almost everywhere, unlike on a chunky part where the extra walls displace infill that was going to be printed anyway.
- Infill. Barely matters. There is very little interior in the model for infill to occupy.
- Material. The volume is fixed, so the mass follows density directly. The same hull is 12.7 g in ABS and 38.7 g in metal-filled PLA — $0.30 of plastic against $2.71.
Why it is a good calibration reference
Print one, weigh it, and compare with what your slicer predicted. The ratio between those two numbers is your machine's own correction factor, and it silently folds in purge, prime lines, flow calibration error and filament diameter variation — everything no model captures.
Applying that ratio to future estimates will beat any published figure, including this one. Most machines land within a few percent; a machine that is out by a fifth has a flow calibration problem worth fixing before anything else.
Weighing a Benchy is also the cheapest way to catch a wrong density in a filament profile. If the slicer predicted 15 g and the boat comes off the plate a gram heavier, the profile is describing a lighter plastic than the one actually on the spool.
Converting it to money
At $22 a kilogram, 15 g of PLA is 33 cents of plastic. The whole print, with power and machine time, comes to about 48 cents.
Swap the density for whatever is loaded and the length and weight converter will give you the hull's mass in that material. The cost calculator turns it into money.