Use a measuring tape (or a cloth strip that you can measure after measuring your body)
And measure according to the following guidelines:
Bust - It is recommended to measure the circumference of the chest when wearing a bra that holds well. Insert the tape measure under the armpit, around the back and complete the circumference.
Waist - The waist circumference is measured at the narrowest part of the body. Surround the area above the navel and below the ribs, and around the back. It is advisable to take another measure with your finger under the tape.
Hips - Press the hips together and measure the circumference at their fullest part.
Torso - body length - surround the front and back of the body and join the ribbon at the groin or shoulder