The need of carbon (C) stock estimation in watershed scale is quite very important. The C stock in ecological boundaries, as watershed areas plays specific role in landscape management. Their value should have to be accurate, measurable and acceptable. Accurate means the estimation should be done through micro scale, from tree or species level, scaling up to land use level. Measurable means the result should be in unit widely known interdisciplinary. Acceptable means the value should be in acceptable range and in logically amount. The aims of this research are to introduce the accurate, measurable and acceptable method to estimate C at watershed scale, and then to figure out the appropriate ecosystem services should be provided by the communities in surrounding watershed. In this research, the estimation includes biomass, necromass and soil organic matter (SOM) in above-below ground. Above-ground include tree, understorey, necromass and litter, while in below ground assessed root biomass and SOM. Scaling up technology was used started from C contents in scale of plant, plot, land use and watershed, respectively. Four watersheds were selected for cases study, namely Cisadane (CS), Ciliwung (CL), Cimandiri (CM) and Cibuni (CB) watershed. The results of C stock at watershed scale are still within acceptable value.