How To Size A V Belt. High flexibility, suitable for flat belt transmission. An additional option is to wrap a small diameter string/rope around the belt, then measure the length of the string.
Was your belt sitting at the top, maybe with the belt hanging slightly over the flanges of the pulley? High flexibility, suitable for flat belt transmission. Belts are not measured by diameter nor folding the belt in half.
For type b, you subtract 3 inches.
I currently maintain a piece of machinery ca.1900 that uses just such a belt. This section is sorted by belt size, so the largest belt is always listed last. C (7/8) d (1 1/4) e (1 1/2) measuring belt length with an old v belt place a mark on the side of an old v belt with a white paint marker. Was your belt sitting at the top, maybe with the belt hanging slightly over the flanges of the pulley?