A wearable device, a charger, and a method for estimating absorbance of the wearable device are provided. The wearable device includes a spectroscope configured to emit a first light to a reference material of a charger, measure an intensity of the first light reflected from the reference material, emit a second light to a skin of a user, and measure an intensity of the second light reflected from the skin of the user； and a processor configured to determine absorbance of the skin of the user based on the intensity of the first light and the intensity of the second light.
