The present invention relates to a device, system and method for determining at least one vital sign of a subject. The device (130) comprises an input interface (131) configured to obtain at least three detection signals (210) derived from detected electromagnetic radiation transmitted through or reflected from a skin region of a subject, wherein each detection signal comprises wavelength-dependent reflection or transmission information in a different wavelength channel, a vital sign extraction unit (132) configured to extract multiple candidate vital signs (232) of the same type of vital sign from said at least three detection signals, wherein each candidate vital sign is extracted from a different detection signal or a different combination of at least two detection signals, a vital sign determination unit (133) configured to determine a final vital sign (233) from said multiple candidate vital signs, and a reliability information unit (134) configured to provide reliability information (234a) indicating the reliability of said final vital sign and/or one or more of said candidate vital signs and to provide unreliability source information (234b) indicating the source of unreliability of said final vital sign and/or one or more of said candidate vital signs.
