Expected statistical uncertainties at future e

In future colliders, the frontiers of luminosity and energy are extended to explore the physics of elementary particles at extremely high precision, and to discover new phenomena suggested from current experimental anomalies. In this letter, we present a method to estimate the expected statistical uncertainties of scattering cross-sections at future colliders using their conceptual design reports. In particular, the expected statistical uncertainties of muon pair production cross-section at the Future Circular Collider (FCC-ee) and the Circular Electron-Positron Collider (CEPC) are calculated. The results can be used to set a goal for systematic uncertainty improvement, to determine the standard model parameters accurately, and to identify the viable parameter space of new physics models. This method is applicable to physical processes with relatively small cross-sections compared to the total inclusive cross-section.