This page acts as a damage calculator and will show you the exact damage of the player's tears as they would be in-game with certain item setups. It's quite simple to use, just click on the images to select them and choose a character and it will emulate that setup from within the game and give you the damage value.
For more information about damage calculations, see Twinge's Spreadsheet.
Note: the interactions between some multipliers (poly, sacred, tech2, thin odd mush) have not yet been tested in Rebirth.