This information turned out surprisingly easy to find. The Boston Tea Party museum website lists the following facts:
- 342 chests on three ships
- 92,000 pounds (roughly 46 tons)
- reported damage £9,659
- equivalent to $1,700,000 in todays money
I would be very careful with the total weight stated, particularly because the one chest I could find definitely didn't hold 120 kg (then again, nobody says that all chests were of the same size). As to the stated damage, according to this book the source is the Boston Gazette from 30 May 1774. This number is quoted in most other places as well, yet there is another estimate mentioning £18,000. For example, here you can read:
the value of the tea thrown into the sea at Boston in 1773 is estimated at 18 thousand pounds sterling, at eighteen pence per pound
Given that a pound sterling was equivalent to 240 pence this estimate apparently assumes 240,000 pounds of tea. I consider that number rather unlikely and it is unclear where it comes from. Maybe damage from similar accidents has been added up here and attributed to the Boston Tea Party.
Now it is a big question how much £9,659 would be worth in todays money, most estimates I've seen are significantly lower than the one mentioned above (a million US dollar or less). This article gives various estimates for the historical value of a pound sterling but after reading it you are probably no wiser than before. Let's go for a simplification, the article The Wealth of Women, 1774 uses the following approximation:
I conclude it fair to say that what could be purchased for one
pound sterling in 1774 would cost on the average about $76 in 1982.
The USA inflation calculator tells us that 1982 prices have to be multiplied with 2.35 to get 2011 prices. Consequently we get 9,659 * 76 * 2.35 = $1,725,097. Wow, that's remarkably close to the value calculated by the museum.