Too many variables. Is it a ten yard truck? Or does it have a 14 yard body? Does it have two axles or three?
Here again if you are asking so that you can get a Class B License instead of Class A. The answer is yes you can use Class B to drive dump trucks. Those of us whom have a class A license can drive any truck and are not limited to just dumptrucks
Short of taking it to a CAT scale, we could give you a rough guess from looking at it if you post a picture.
Aluminum or steel box, frame thickness, rear axle ratings, fuel tank size, hydraulic tank size. Yup. Wayyy too many variables.