Universal time (UT1) is an indispensable parameter in applications of geodesy and navigation. Currently, an UT1 parameter per day can be obtained from the international Earth rotation service (IERS). However, UT1 parameters cannot be measured and obtained in real time on any day. Large-scale fiber optic gyroscopes (FOGs) can measure and provide high-temporal-resolution measurements of variations in the Earth’s rotation angular rate; thus, FOGs may provide a way to monitor UT1 in real time. Herein, we report the design of a novel UT1 calculation method based on the existing large-scale FOG measurement platform and the basic principles of FOG measurement. Data measured from FOG by this new method are analyzed to verify the method’s accuracy and feasibility for implementation. The UT1 parameters are preliminarily calculated by measuring data from the large-scale FOG; the time interval for UT1 parameter acquisition is also shortened to 5 min. Thus, based on the large-scale FOG, the proposed method has the potential to become a new method of UT1 measurement.