If you already have a U.S. belt with a leather loop and "puppy paw" plate and you want something that is more appropriate for the last two years of the war, we'll be offering copies of the mid/late war U.S. waist belt with a brass keeper and plate with arrow-shaped hooks.  And these belts will include exclusive 1863 Watertown Arsenal stamps too.
 
To get the right fit, you need to measure your waist where you wear your belt, in inches.  If you provide your pants size, you're going to get a belt that is far too small.  Take a string, wrap it around yourself, and measure the string.  Or measure a Civil War belt you already wear from the prong on the buckle to the adjustment hole that you use.  The center hole on these belts will be placed at the measurement you provide, so if it doesn't fit that's on you.