A skin treatment device, in particular a hair removal device, comprising a light emission unit comprising a substrate and a plurality of first LED dies mounted on the substrate on an area of at least 0.2 c m2, in particular of at least 1 c m2, wherein the skin treatment device is arranged to activate the first LED dies to emit a treatment light pulse having a pulse length in particular in the range of between 10 ms and 300 ms and the first LED dies have a radiant flux such that a radiant fluence on the skin of a user of at least 1 J/cm 2 is achieved by application of the treatment light pulse, wherein the light emission unit has at least two selectable active areas (A1; A2) of first LED dies, where the selectable active areas (A1; A2) have different sizes, and at least three second LED dies are mounted on the substrate at locations suitable for visibly indicating each of the selectable active areas (A1; A2), wherein the second LED dies are disposed at corners or end points of the selectable active areas (A1; A2) of first LED dies or are mounted in close proximity to such corners or end points of the selectable active areas (A1; A2) of first LED dies; and the skin treatment device further comprises a control unit for controlling the first and second LED dies (102, 103), the control unit being arranged for activating only the first LED dies assigned to the selected active area (A1; A2) to emit the treatment light pulse and for activating only the second LED dies assigned to the selected active area (A1; A2) to emit visible light outside of the duration of the treatment light pulse to visibly indicate the selected active area (A1; A2). a light emission unit comprising a substrate and a plurality of first LED dies mounted on the substrate on an area of at least 0.2 c m2, in particular of at least 1 c m2, wherein the skin treatment device is arranged to activate the first LED dies to emit a treatment light pulse having a pulse length in particular in the range of between 10 ms and 300 ms and the first LED dies have a radiant flux such that a radiant fluence on the skin of a user of at least 1 J/cm 2 is achieved by application of the treatment light pulse, wherein the light emission unit has at least two selectable active areas (A1; A2) of first LED dies, where the selectable active areas (A1; A2) have different sizes, and at least three second LED dies are mounted on the substrate at locations suitable for visibly indicating each of the selectable active areas (A1; A2), wherein the second LED dies are disposed at corners or end points of the selectable active areas (A1; A2) of first LED dies or are mounted in close proximity to such corners or end points of the selectable active areas (A1; A2) of first LED dies; and the skin treatment device further comprises a control unit for controlling the first and second LED dies (102, 103), the control unit being arranged for activating only the first LED dies assigned to the selected active area (A1; A2) to emit the treatment light pulse and for activating only the second LED dies assigned to the selected active area (A1; A2) to emit visible light outside of the duration of the treatment light pulse to visibly indicate the selected active area (A1; A2).