An apparatus comprising at least one data processing device for designing blasting order of drill holes of a face drilling pattern of a round, and wherein a face of the round defines a first free surface for the blasting; the apparatus is provided with data on drill holes of the face drilling pattern and available time delays of the blast; the apparatus is configured to design a blasting sequence for the drilling pattern by dividing the blast into several successive time delays following an initial blasting creating an initial second free surface for the blast; characterized in that the apparatus is configured to allow selection of one or more drill holes for each greater time delay wherein the drill holes are surrounding previously formed second free surface defined by drill holes having shorter time delay than the examined time delay and the drill holes form a drill hole set for the examined time delay; the apparatus is configured to determine burst volumes (V B) for each subsequent time delay based on input data on the selected drill hole set and data on the expanding second free surface; the apparatus is configured to determine free volume (V F) for each subsequent time delay, wherein the free volume (V F) is defined by the expanding second free surface and length of the round; and the apparatus is configured to multiply the determined burst volumes (V B) for each time delay with an input swell factor and is configured to compare the products of the multiplications with the determined free volumes (V F) of corresponding time delays, and is configured to only allow selection of drill hole sets wherein the products of the multiplications are minor than the determined free volumes (V F). the apparatus is provided with data on drill holes of the face drilling pattern and available time delays of the blast; the apparatus is configured to design a blasting sequence for the drilling pattern by dividing the blast into several successive time delays following an initial blasting creating an initial second free surface for the blast; characterized in that the apparatus is configured to allow selection of one or more drill holes for each greater time delay wherein the drill holes are surrounding previously formed second free surface defined by drill holes having shorter time delay than the examined time delay and the drill holes form a drill hole set for the examined time delay; the apparatus is configured to determine burst volumes (V B) for each subsequent time delay based on input data on the selected drill hole set and data on the expanding second free surface; the apparatus is configured to determine free volume (V F) for each subsequent time delay, wherein the free volume (V F) is defined by the expanding second free surface and length of the round; and the apparatus is configured to multiply the determined burst volumes (V B) for each time delay with an input swell factor and is configured to compare the products of the multiplications with the determined free volumes (V F) of corresponding time delays, and is configured to only allow selection of drill hole sets wherein the products of the multiplications are minor than the determined free volumes (V F).