A blank for forming a disposable cup, the blank comprising a cardboard sheet designed to be formed into a body of a cup, preferably in a form of a truncated cone, the blank comprising - a first edge in a form of a first arc for forming the bottom edge of the cup, - a folding line for forming the rim of the cup, wherein the folding line for forming the rim of the cup contains a first folding line formed by a plurality, such as 4-10, of interconnected arc-shaped folding lines each arcing to the opposite direction than the first arc, and wherein a foldable wing extends form each arc-shaped folding line , wherein tips of the wings are configured to be folded towards the center of the formed cup to lock onto each other to form a cover over the opening of the cup, each of the foldable wings extending form each arc-shaped folding line are partly interconnected at the folding line end forming a continuous area between the first folding line and a second edge at the opposite end of the blank than the first edge , the continuous area being in a form of an arc which is substantially parallel to the first folding line , wherein each of the foldable wings contain at the continuous area a first folding surface formed by a second folding line and a third folding line , the second and the third folding lines extending from the first end and the second end of each arc-shaped folding lines and forming an angle (α), such as an angle (α) of 40-50°, wherein the tip of a wing points away from the first folding line , and wherein the second folding line and the third folding line are formed to be able to fold to form the cover, preferably wherein a second folding line of a wing and a third folding line of an adjacent wing meet each other at an end of an arc-shaped folding line, characterised in that the tips of the wings extend from the second edge . - a first edge in a form of a first arc for forming the bottom edge of the cup, - a folding line for forming the rim of the cup, wherein the folding line for forming the rim of the cup contains a first folding line formed by a plurality, such as 4-10, of interconnected arc-shaped folding lines each arcing to the opposite direction than the first arc, and wherein a foldable wing extends form each arc-shaped folding line , wherein tips of the wings are configured to be folded towards the center of the formed cup to lock onto each other to form a cover over the opening of the cup, each of the foldable wings extending form each arc-shaped folding line are partly interconnected at the folding line end forming a continuous area between the first folding line and a second edge at the opposite end of the blank than the first edge , the continuous area being in a form of an arc which is substantially parallel to the first folding line , wherein each of the foldable wings contain at the continuous area a first folding surface formed by a second folding line and a third folding line , the second and the third folding lines extending from the first end and the second end of each arc-shaped folding lines and forming an angle (α), such as an angle (α) of 40-50°, wherein the tip of a wing points away from the first folding line , and wherein the second folding line and the third folding line are formed to be able to fold to form the cover, preferably wherein a second folding line of a wing and a third folding line of an adjacent wing meet each other at an end of an arc-shaped folding line, characterised in that the tips of the wings extend from the second edge . <EOS>