A method of packaging at least one product in a box comprising the steps of: - measuring the size of the at least one product - determining the length L, the width W and the height H of the box closely adapted to the size of the at least one product to be packed in the box, the box having a top, a bottom and four lateral walls, the first and second ones, respectively the third and fourth ones being opposite each other - choosing a one piece blank of a corrugated cardboard sheet material in a stack, this blank being designed for forming a belt (2, 3, 6, 7) intended to form said box having the length L, the width W and the height H, wherein this blank includes a main rectangular body (10, 40) extending along a longitudinal direction and two protruding rectangular parts (11, 12; 41, 42) extending in a transverse direction and symmetrically with regard to the main body, so as to define two perpendicular branches, a first branch being defined by the main body and a second branch defined by the protruding parts, the main body (10, 40) having a width larger than the length L and a length larger than at least twice the width W plus the height H (2W + 2H) and each of the protruding parts having a length larger than the height H or the width W and a width larger than the width W or the height H, the choice of the blank is made between a predetermined number of different available blanks having different dimensions stacked in different stacks of blanks, each stack corresponding to one type of blanks, so that the chosen blank has the dimensions closest to the ones of the final box in order to reduce the waste, - manufacturing a belt from said blank, said belt (2, 3, 6, 7) having four rectangular main panels (20 to 23, 30 to 33, 60 to 63, 70 to 73) forming the top, the bottom and the first and second lateral walls of the box, one of the main panels (21, 31; 60, 70) being provided on each of two opposing sides with a secondary panel (28, 38, 68, 78) forming the third or the fourth lateral wall of the box, wherein, after removal of the blank (1, 4) from the stack, it is then cut to reduce the length and/or the width (Dl, d1; D2, d2) of the branches of the blank so that they are adapted to the dimensions of the belt (2, 3, 6, 7) and wherein two first parallel fold lines (14, 44) are created between the main body and the protruding parts to define the secondary panels (28, 38, 68, 78) and at least three second parallel fold lines (16, 46) are created in the main body (10, 40) to define the four main rectangular panels (20 to 23, 30 to 33, 60 to 63, 70 to 73), the first fold lines being perpendicular to the second fold lines, - erecting the box by folding the belt along the said first and second fold lines (14, 44, 16, 46, 17) - placing the at least one product in the box and - closing the box. - measuring the size of the at least one product - determining the length L, the width W and the height H of the box closely adapted to the size of the at least one product to be packed in the box, the box having a top, a bottom and four lateral walls, the first and second ones, respectively the third and fourth ones being opposite each other - choosing a one piece blank of a corrugated cardboard sheet material in a stack, this blank being designed for forming a belt (2, 3, 6, 7) intended to form said box having the length L, the width W and the height H, wherein this blank includes a main rectangular body (10, 40) extending along a longitudinal direction and two protruding rectangular parts (11, 12; 41, 42) extending in a transverse direction and symmetrically with regard to the main body, so as to define two perpendicular branches, a first branch being defined by the main body and a second branch defined by the protruding parts, the main body (10, 40) having a width larger than the length L and a length larger than at least twice the width W plus the height H (2W + 2H) and each of the protruding parts having a length larger than the height H or the width W and a width larger than the width W or the height H, the choice of the blank is made between a predetermined number of different available blanks having different dimensions stacked in different stacks of blanks, each stack corresponding to one type of blanks, so that the chosen blank has the dimensions closest to the ones of the final box in order to reduce the waste, - manufacturing a belt from said blank, said belt (2, 3, 6, 7) having four rectangular main panels (20 to 23, 30 to 33, 60 to 63, 70 to 73) forming the top, the bottom and the first and second lateral walls of the box, one of the main panels (21, 31; 60, 70) being provided on each of two opposing sides with a secondary panel (28, 38, 68, 78) forming the third or the fourth lateral wall of the box, wherein, after removal of the blank (1, 4) from the stack, it is then cut to reduce the length and/or the width (Dl, d1; D2, d2) of the branches of the blank so that they are adapted to the dimensions of the belt (2, 3, 6, 7) and wherein two first parallel fold lines (14, 44) are created between the main body and the protruding parts to define the secondary panels (28, 38, 68, 78) and at least three second parallel fold lines (16, 46) are created in the main body (10, 40) to define the four main rectangular panels (20 to 23, 30 to 33, 60 to 63, 70 to 73), the first fold lines being perpendicular to the second fold lines, - erecting the box by folding the belt along the said first and second fold lines (14, 44, 16, 46, 17) - placing the at least one product in the box and - closing the box.