I've been seeing the 330 m and 110 m length estimates for 1.75 and 3.0 mm spools (of PLA, presumably). But a moment's thought staring at that will raise an obvious question.
Using πr², we get the area of the filament in square millimeters (rounding to two decimal points)
For 1.75 it's 2.41 mm²
For 3.00 it's 7.07 mm²
Then taking the ratio and multiplying:
(2.41/7.07) * 330 m = 112 m which is close enough to 110 m.
BUT as all makers of filament and makers of extruders know, 3.00 mm is just a rounding off of the real dimension, which is 2.85 mm. Now do that:
For 2.85 it's 6.38 mm²
(2.41/6.38) * 330 m = 125 m which is at least 120 m.
So, whoever calculated the approximation of 110 m did the calculation based on the rounded rather than actual dimension. What am I missing here?
My point is not that the 330 and 110 would be inaccurate given the dimensions of 1.75 and 3.00. Rather, my point is that the 3.00 mm diameter is not what is really so; it's actually 2.85 mm and therefore the answer is longer than 110 m.