Inductance Factor ($A_L$): The inductance of a core per square of the number of turns.

$L = A_L \cdot N^2$ (where L is usually in nH and AL is in $nH/N^2$)

$N = \sqrt{\frac{L}{A_L}}$

$A_L = \frac{L}{N^2}$

Transformers:

Voltage Ratio: $\frac{V_s}{V_p} = \frac{N_s}{N_p}$

Impedance Ratio: $\frac{Z_s}{Z_p} = \left(\frac{N_s}{N_p}\right)^2$