The waistband is designed to be worn on your waist but can be worn on the hip too (make sure you account for that when choosing the right size, as the hip is often wider than the waist). Note that the waistbands have quite a lot of stretch to them.

Front Pocket Size (all) = 10cm x 19cm - Most phones also fit onto the side pockets

This fits even the largest phones on the market.
E.g. iPhone 11 Pro Max = 7.8cm x 15.8cm
E.g. Samsung Galaxy Note 10+ = 7.7cm x 16.2cm 
E.g. Iphone 11 = 7.6cm x 15.1cm 

Waistband stretch factor ≈ 180% (i.e. a 10cm length of the elastic waistband can be stretched to ≈ 18cm)

Size - XS
Waistband width (measured flat/un-stretched) = 32cm
Waistband circumference (un-stretched) = 64cm

Waistband width (stretched to maximum) = 48cm
Waistband circumference (stretched to maximum) = 96cm

Note: It is not recommended to wear the waistband stretched to maximum as it will be uncomfortable. The stretched to max figures is for illustrative purposes only.

64-78cm suggested waist circumference – recommended for those who usually wear leggings in XS

Size - S/M

Waistband width (measured flat/un-stretched) = 36cm
Waistband circumference (un-stretched) = 72cm

Waistband width (stretched to maximum) = 56cm
Waistband circumference (stretched to maximum) = 112cm

Note: It is not recommended to wear the waistband stretched to maximum as it will be uncomfortable. The stretched to max figures is for illustrative purposes only.

76-90cm suggested waist circumference – recommended for those who usually wear leggings in S or M

Size - L/XL

Waistband width (measured flat/un-stretched) = 40cm
Waistband circumference (un-stretched) = 80cm

Waistband width (stretched to maximum) = 60cm
Waistband circumference (stretched to maximum) = 120cm

Note: It is not recommended to wear the waistband stretched to maximum as it will be uncomfortable. The stretched to max figures is for illustrative purposes only.

86-112cm suggested waist circumference – recommended for those who usually wear leggings in L or XL

The above recommendations are merely suggestions as we acknowledge that preferential fit is very individual and subjective (especially if you hover between sizes)