A capsule for preparation of a beverage from a brewing device, and a system including the capsule and brewing device. The capsule includes a lateral wall, a water inlet wall and an outlet wall forming a hollow body where a brewing product is contained. The hollow body has a central axis passing through the inlet and outlet walls. At least one portion of the inlet wall extends along an ellipse curve as defined by a circumference, having a diameter substantially equal to the maximum diameter of the lateral wall of the capsule lying on a plane inclined at an angle with respect to a first plane perpendicular with respect to the central axis of the capsule, the planes intersecting at an axis, the circumference being projected on a plane perpendicular to the first plane containing an axis selected from the intersection axis or an axis parallel to the intersection axis.