If you want your pants to look good, they must fit your body well. Men should start by measuring their natural waist. The natural waist is the measurement straight around your body at your belly button. The tape measure should not be tight or loose, but right against the skin. If your waist doesn't exactly hit the mark, round up to the nearest inch.
For the inseam, men should measure from the groin to the lower part of the ankle down the inside of the leg. Men's pants are measured at the waist and inseam, with the waist measurement first, according to WikiHow.
Women should also get the measurement for their natural waistline. This is usually right above the belly button. You should be measuring at the thinning part of your midsection. This is the waist measurement. You'll also want to take an inseam measurement. These two measurements can be converted into women's sizes using a standard size conversion chart.