Measure directly on the body.
The measure tape must be horizontal at all times.
Your hip measurement is leading.
If a measurement is between two sizes, order the smaller size for a tighter fit or the bigger size for a looser fit.
Measure around the thigh 2.5 cm below crotch under the buttocks.
Measure around waist at the smallest part, just above the navel.
Measure around hip at the fullest part of buttocks.