Why does my Prusament spool read differently from the preset?

Figures for the original spool already span about 10 g, and the cardboard center gains and loses a few grams with humidity. If you have the newer plastic-core spool, the one figure we found is much heavier, about 280 g. For tighter numbers, weigh yours and use Custom.

Doesn't Prusa publish the exact data for my spool?

Close. Prusa publishes no general empty weight, but each Prusament spool has a code that links to its manufacturing record, and Prusa's spool-check tool uses that data to convert your measured spool-plus-filament weight into remaining length. This page is for the fast version: scale, subtract, done.

Does the preset work for every Prusament product?

Only for the original 1 kg spool. Larger spools, refills and the redesigned spool are different; weigh those once before trusting any preset.

Empty spool weights

Prusament empty spool weight, measured instead of guessed

Original 1 kg spool

191-201 g

Redesigned NFC spool (one entry)

~280 g

Prusament's original spool, with black plastic sides and a cardboard center, comes to 191 to 201 g empty in the figures owners have posted. The calculator below starts at 194 g, the middle of those figures. Prusa publishes no general empty weight, and humidity moves the cardboard center a few grams.

In October 2025 Prusa introduced a redesigned spool with a plastic core instead of the cardboard one. The one figure we found for it, a community database entry for 0.8 kg of ASA, is 280 g, so weigh one before relying on the older number. Prusa's spool-check web tool uses each spool's own manufacturing data to turn your measured weight into remaining length.

Prusament spool weights at a glance

Spool and what is on the scale	Empty weight (g)	Evidence
Original 1 kg spool Empty spool: black plastic sides and cardboard center	~194 (191-201) g empty	User measurements Measurements of 191, 192.8, 193.8 and 200 g (2020-2021), plus 201 g from Prusa's per-spool data quoted by an owner (2019). Source 1 Source 2 Source 3
Redesigned NFC spool (from October 2025) Plastic sides and plastic core; entry is for a 0.8 kg ASA spool	~280 g empty	Community database One community database entry. Prusa describes the redesign (plastic core, recycled polycarbonate) but publishes no general empty weight. Weigh one empty spool and use Custom. Source 1 Source 2

“Manufacturer” means the brand publishes the number. “User measurements” means people weighed their own spools and posted the result, so your spool can differ. The exact answer takes one minute: weigh an empty spool of the type you use, write the number on it, and pick Custom in the calculator from then on.

What a wrong tare does to your answer

Every gram of tare error moves the remaining-filament answer by the same gram. Say the scale reads 300 g and you are unsure whether the tare is 200 g or 225 g. One gives 100 g of filament left, the other 75 g. For an 80 g print, that is the difference between 20 g to spare and 5 g short. When a print is close, weigh an empty spool of the same type before you trust any preset.

How to weigh it right

Take the spool off the printer or out of the AMS. Anything supporting the spool skews the reading.
Use a kitchen scale on a flat surface. Gram resolution is plenty; you do not need a lab scale.
Enter the total weight above, pick the matching spool type, and read off grams remaining. The result updates as you type.

Frequently asked

Why does my Prusament spool read differently from the preset?: Figures for the original spool already span about 10 g, and the cardboard center gains and loses a few grams with humidity. If you have the newer plastic-core spool, the one figure we found is much heavier, about 280 g. For tighter numbers, weigh yours and use Custom.
Doesn't Prusa publish the exact data for my spool?: Close. Prusa publishes no general empty weight, but each Prusament spool has a code that links to its manufacturing record, and Prusa's spool-check tool uses that data to convert your measured spool-plus-filament weight into remaining length. This page is for the fast version: scale, subtract, done.
Does the preset work for every Prusament product?: Only for the original 1 kg spool. Larger spools, refills and the redesigned spool are different; weigh those once before trusting any preset.

Where these numbers come from

Each row above names its evidence. Sources were last checked October 10, 2026. Spool designs change without notice, so if your spool disagrees, trust your scale over any table, including this one.

Correction note: October 10, 2026: the preset changed from 200 g to 194 g, the middle of the figures we could trace. The previous 192 to 207 g range had an upper end we could not find in any source.