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.
Chest:
Measure around the thigh 2.5 cm below crotch under the buttocks.
Waist:
Measure around waist at the smallest part, just above the navel.
Hips:
Measure around hip at the fullest part of buttocks.