This Recommendation describes service functionalities of self-quantification over Internet of things (IoT) with the purpose of fostering interoperability of self-quantification services. The following elements are within the scope of this Recommendation. - Concept@ technical implications@ and general service models to clarify the idea of selfquantification services and to categorize them into three different service models. - Considerations to emphasize three important aspects of self-quantification services. - Requirements to specify three different categories of requirements@ which support the identified considerations. - Functionalities to define a general functional architecture based on the identified requirements and to illustrate sequential diagrams of three different service models. This Recommendation builds on the overview of IoT [ITU-T Y.4000] and the common requirements of the IoT [ITU-T Y.4100]@ providing specific requirements in support of self-quantification application domain. Usage scenarios of self-quantification services are provided in Appendix I. NOTE ?C Regulatory@ legal and business aspects are outside the scope of this Recommendation.