Body Length: Measure from the highest point on the shoulder straight down to the bottom hem.
Chest: Measure 1" below the armhole, straight across the chest from seam to seam.
Sleeve Length: Measure from the center back of the neck to the shoulder point, then down to the end of the sleeve.
Shoulder Width: Measure straight across the back from shoulder seam to shoulder seam.
Hem Width: Measure straight across the bottom edge of the hoodie.
Sweatpants:
Waist: Measure straight across the waistband from one side to the other. Double the number for the full waist measurement.
Hip: Measure straight across the fullest part of the hips, about 7–9" below the waistband.
Inseam: Measure from the crotch seam straight down to the bottom hem.
Outseam: Measure from the top of the waistband down to the bottom hem.
Leg Opening: Measure straight across the bottom hem of one leg.
T-Shirts:

Body Length: Measure from the highest point on the shoulder straight down to the bottom hem.
Chest: Measure 1" below the armhole, straight across the chest from seam to seam.
Shoulder Width: Measure straight across the back from shoulder seam to shoulder seam.
Sleeve Length: Measure from the shoulder point to the end of the sleeve.
Hem Width: Measure straight across the bottom edge of the tee.
Hoodies:
Body Length: Measure from the highest point on the shoulder straight down to the bottom hem.
Chest: Measure 1" below the armhole, straight across the chest from seam to seam.
Sleeve Length: Measure from the center back of the neck to the shoulder point, then down to the end of the sleeve.
Shoulder Width: Measure straight across the back from shoulder seam to shoulder seam.
Hem Width: Measure straight across the bottom edge of the hoodie.
Sweatpants:
Waist: Measure straight across the waistband from one side to the other. Double the number for the full waist measurement.
Hip: Measure straight across the fullest part of the hips, about 7–9" below the waistband.
Inseam: Measure from the crotch seam straight down to the bottom hem.
Outseam: Measure from the top of the waistband down to the bottom hem.
Leg Opening: Measure straight across the bottom hem of one leg.