Embodiments of the present disclosure relate to a method, an electronic device, and a computer program product for backing up data. The method comprises: determining historical information of a storage space for backing up the data, the historical information indicating a historical size of the storage space configured to store the data within a historical time period, a size of the data being changeable within the historical time period; determining change information of the historical size of the storage space based on the historical information; determining, based on the change information, a probability that a size of the storage space to be configured to back up the data reaches a predetermined size; and adjusting, based on a determination that the probability is higher than or equal to a predetermined threshold, a backup policy for backing up the data to reduce the probability. By using the technical solution of the present disclosure, a backup system can pre-adjust a backup policy by determining a change trend of use of a storage space for backing up data, so that a backup failure will not be caused by an insufficient storage space, and an original backup policy can be recovered automatically when a size of the storage space is increased.