Filament Spool Calculator

Estimate how much filament you have left on an open spool by weighing it.

Spool Details

Spool Brand / Type

Current Total Weight (g)Weigh the spool with filament

Material Specs

Material

Diameter (mm)

Remaining

Filament Weight

355 g

Estimated Length

119.0 m

Assuming an empty spool weight of roughly 245g. This is an estimate; actual weights vary by batch.

Why weigh your spools?

It happens to everyone: you have a long print (e.g., 20 hours) and three partially used spools of the same color. Slicers tell you the print needs 450g of filament. Do you have enough on that half-empty roll?

By weighing the spool and subtracting the empty spool's weight, you get the exact weight of the plastic remaining.

Pro Tip: When you open a fresh spool, weigh it before using it! Subtract 1000g (or the filament net weight) to get the exact empty spool weight for that specific roll. Write it on the side label.

Database & Accuracy

Our database uses community-averaged weights. Manufacturers often change spool designs (e.g., switching from plastic to cardboard), which changes the weight significantly.

Plastic Spools: Usually 195g - 250g.
Cardboard Spools: Usually 125g - 200g.
Reusable / Master Spools: Often ~250g including clips and inserts.

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