How Long Is 1 kg of PLA Filament?

by | Mar 23, 2021

3D printing filament is always sell in spools classified by weight. They are often in 500-gram or 1-kilogram spools, although there are both bigger and smaller options. This is likely the most convenient unit of measurement in terms of sales and logistics.

Unfortunately, it’s easier to estimate how long a spool would last if you knew exactly how long the filament is. Here is a handy way to calculate the meters of filament in your spool given its weight.

How To Calculate?

Calculating the meters of filament in a spool requires only basic math. However, there are some values that you need to know beforehand. To make this demonstration easier to understand, let’s assign values based on a theoretical spool of 1.75 mm PLA filament.

Needed values:

Weight of the filament =1 kilogram or 1000 grams

Density of the filament = 1.24 grams / cm3 (for PLA)

Diameter of the filament =<1.75 mm or 0.175 cm

Calculations:

Cross-sectional area of the filament = Π * (Diameter/2)2

Volume of the filament = Weight / Density

Length of the filament = Volume / Cross-sectional

Based on our calculations, around 335 meters of filament in a 1-kilogram spool of PLA filament with a diameter of 1.75 millimeters. Please note that these calculations assume that the filament diameter is perfectly consistent throughout its length.

You can use this method for any spool. You can also estimate the length of leftover filament in a spool that is partially consumed. Suppose you have a weighing scale at home. Just make sure to account for the weight of the empty spool.