Here you can calculate points for an arbitrary mahjong hand (Chinese Official rules).
To add a melded set choose a set type by clicking a radio button on the right and then for the pung, melded or concealed kong click corresponding tile in the table of tiles on the left, for the chow click the middle tile of a chow. Concealed part of the hand should be added tile-by-tile. Also you should define the winning tile and the method: from discard or from the wall. Additional parameters and the current winds settings are also available.
The hand can be edited (sets and tiles can be deleted from the hand with simple clicking on them) or totally reset with the "Clear hand" button.