Beginning in early 1863 the Richmond Arsenal manufactured painted cloth waist belts using pre-cut scrap leather leftover from saddle production at the Clarksville Ordnance Harness Shops and varnished iron wire roller buckles.  These belts would be a common style seen in the ANV for the remainder of the war.
 
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.