An apparatus for estimating bio-information may include a sensor configured to emit light to an object and detect light scattered or reflected from the object and a processor configured to acquire, based on an intensity of the detected light, a first absorbance coefficient change and a first scattering coefficient change, relative to a reference time point, acquire a second scattering coefficient change based on the first absorbance coefficient change, and correct the first scattering coefficient change based on the acquired second scattering coefficient change.