A handle for door or window having a movable sash, comprising: - a grip having a gripping portion and a base portion or neck facing, in use, a part of the outer profile or wing of the movable sash; the grip being rotatable about a first axis; - a shaft protruding from the grip and passing, in use, through the outer wing of the movable sash; - a kinematic unit positioned, in use, in the proximity of a longitudinal channel inside the profile of the sash in which at least one control rod slides and is coupled, in use, to the protruding shaft; the kinematic unit being connected to at least one control rod designed for converting the rotational movement of the grip into a translational movement of the rod, in both directions; the kinematic unit comprising: - a first and a second gear wheel (17, 18), different to each other, placed side by side and in contact with each other and having a seat (19, 20) positioned, in use, coaxial with each other and engaged simultaneously by the shaft; - at least one rack having two separate meshing tracks (21a, 21b) placed side by side and engaged by a corresponding gear wheel (17, 18); the rack being formed on a rod-shaped body positioned, in use, parallel to a free upper surface of the channel and provided with means for coupling with the at least one control rod, characterised in that: the toothed surfaces of each track (21a, 21b) of the rack are incised on the rod-shaped body in such a way as to define corresponding tracks (21a, 21b) with hollow meshing surfaces, recessed relative to a reference plane of the rod-shaped body, for the teeth of the first and second gear wheel (17, 18), and wherein each track (21a 21b) is different and separated by a central longitudinal rib. - a grip having a gripping portion and a base portion or neck facing, in use, a part of the outer profile or wing of the movable sash; the grip being rotatable about a first axis; - a shaft protruding from the grip and passing, in use, through the outer wing of the movable sash; - a kinematic unit positioned, in use, in the proximity of a longitudinal channel inside the profile of the sash in which at least one control rod slides and is coupled, in use, to the protruding shaft; the kinematic unit being connected to at least one control rod designed for converting the rotational movement of the grip into a translational movement of the rod, in both directions; the kinematic unit comprising: - a first and a second gear wheel (17, 18), different to each other, placed side by side and in contact with each other and having a seat (19, 20) positioned, in use, coaxial with each other and engaged simultaneously by the shaft; - at least one rack having two separate meshing tracks (21a, 21b) placed side by side and engaged by a corresponding gear wheel (17, 18); the rack being formed on a rod-shaped body positioned, in use, parallel to a free upper surface of the channel and provided with means for coupling with the at least one control rod, characterised in that: the toothed surfaces of each track (21a, 21b) of the rack are incised on the rod-shaped body in such a way as to define corresponding tracks (21a, 21b) with hollow meshing surfaces, recessed relative to a reference plane of the rod-shaped body, for the teeth of the first and second gear wheel (17, 18), and wherein each track (21a 21b) is different and separated by a central longitudinal rib. - a first and a second gear wheel (17, 18), different to each other, placed side by side and in contact with each other and having a seat (19, 20) positioned, in use, coaxial with each other and engaged simultaneously by the shaft; - at least one rack having two separate meshing tracks (21a, 21b) placed side by side and engaged by a corresponding gear wheel (17, 18); the rack being formed on a rod-shaped body positioned, in use, parallel to a free upper surface of the channel and provided with means for coupling with the at least one control rod,