Originally Posted by

**romsek** This can be closely approximated by having $n$ layers of $k$ loops.

The radius of the loops of the $n$th layer is given by $r_n=R+n d$ where

$R$ is the radius of the spool

$d$ is the thickness of the line

There are $k$ loops per layer where $k=\dfrac L d$ where

$L$ is the length of the spool.

The length of a given loop in layer n is $2 \pi r_n$ so the total length of line is given by

$2 \pi r_n n k = 2 \pi (R + n d) n k$

your numbers are

$R=0.5$

$L=1.75$

$d = 0.0157$

plugging these in and solving for length=1000 we find

$k\approx 111.465$

$n \approx 2.64$

or roughly 2 layers and then 71 loops in the 3rd layer. This corresponds to a count of

$count=111.5 \times 2.64 \approx 294$