In order to investigate the mechanisms of mangrove's spatial dynamics, changes in landscape patch count and area caused by various drivers through different dynamic procedures need to be accurately quantified. Based on previous work, two calculation methods, namely accurate measurement method and holistic measurement method, are introduced in this paper. Firstly, two time-period distribution maps of mangrove and remote sensing images were overlaid with geographic information systems (GIS) and all mangrove patches were divided into analysis units, in which each patch was caused by the same driver and changed through the same procedure. Secondly, if the time-1 image could be registered accurately with time-2 image, we used the accurate measurement method. With the overlay methods of lines and polygons, the time-1 polygon layer of mangrove patches was subset by the time-2 line layer of mangrove patches, and the time-2 polygons were subset by the time-1 lines, resulting in several sub-patches in an analysis unit. Each sub-patch was visually interpreted to identify the driver and the dynamic procedure. Subsequently, the amount of changes with regard to the patch count and area of each analysis unit caused by various driving factors through different change ways were calculated. Thirdly, if the earlier image cannot be registered accurately with later image, we used the holistic measurement method. Each analysis unit was visually interpreted to identify the key driver and the major dynamic procedure according to both the level of difficulty in patch recovery and the amount of changes in patch count and area. Accordingly, the differences in patch count and area between the two periods in the analysis unit were regarded as the amount of changes in patch count and area caused by this driver and through this procedure. Both methods could be used to conduct quantitative analysis for the changes in patch count and area. The accurate measurement method is more reliable because it computes changes in patch count and area under various combinations of different drivers and dynamic procedures. Although the holistic measurement method only considers the major driver and dynamic procedure within an analysis unit, its statistics include the gross gain, gross loss, the total changes and net changes in patch count and area within an analysis unit, which also have scientific values and practical significance.