General tips

Keep the tape firm but not tight. If you take your measurements yourself, then it's always good to take them more than once as this will average out any variations in posture.

Collar

Place the tape around the neck. Set the tape low in the back of the neck and bring it around the front to where the collar will button. Add 1/2 inch to your neck measurement to determine your final collar size.

Chest

Measure yourself around the fullest part of your chest,
keeping the tape measure level under the arms and across your back.

Waist

Measure yourself around your natural waistline.

Inside Leg

Measure yourself from the crotch to your ankle bone.