Here you can calculate points in an arbitrary mahjong hand (Chinese Official rules).
To add a set choose set type (chow, pung, melded or concealed kong), then set rank from the rank table (for the chow you have to define the rank of the middle tile). Concealed part of the hand can be added tile by tile. Also you should define the winning tile rank and method: from discard or from the wall. Additional parameters and current winds selections 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" button.