The length of a 1 kg spool of 1.75 mm diameter filament depends on the material’s density. For PLA, which has a density of approximately 1.25 g/cm³, a 1 kg spool contains about 330 meters of filament.
For ABS, with a density of about 1.04 g/cm³, a 1 kg spool contains approximately 400 meters of filament.
The length can be calculated using the formula:

Length (m)= (Mass (g)/Density (g/cm³)) x (1 / π×(d/2)2)

where d is the filament diameter in mm

The density of PETG filament typically ranges from 1.23 to 1.27 g/cm³, with most sources citing 1.27 g/cm³ as a common value. This makes PETG one of the denser 3D printing filaments, similar to PLA.

Given this density and a 1.75 mm diameter, a 1 kg spool of PETG contains approximately 327 meters of filament.