A reflectance-based optical measurement device and a method for a reflectance-based optical measurement are provided. The device comprises an illumination and detection assembly configured to output light to a surface portion of a user for measurement and to detect the output light reflected from said surface portion of the user as a signal a coupling member configured for coupling in a cableless configuration to a personal mobile processing device a measurement surface configured to allow access to said measurement surface by the surface portion of the user wherein said access is provided by the optical device being holderless such that the surface portion of the user is allowed access to said measurement surface from all directions in a single plane and further wherein said coupling member is arranged to transmit the detected signal to the personal mobile processing device.
