A method of measuring superconducting critical current in persistent mode using superconducting closed loops which allow the persistent current to flow without any joints. This persistent critical current is different than traditional resistive critical current that is the upper limit of the superconducting current carrying capacity, and provides the information about the range of critical current in persistent mode that is more close to applications in MRI, SMES, and Maglev operations. The measurement can be used as a quality control method in the manufacturing process and a piece of crucial information to magnet manufacturers for the design and fabrication of magnet. The superconducting materials include the second generation superconducting wires (coated conductors) based on Rare Earth (RE) Barium Copper Oxide superconducting material (REBa2Cu3O6+x, REBCO), or any other type of superconducting wires that can be manufactured in the form of tape.