There is a huge discrepancy in reports of the size of the Chelyabinsk meteor. Some apparently reliable sources put it at 10-30 tons, while others have it at 7,000-10,000 tons. This is an enormous discrepancy. Can we figure out which one is correct?
All accounts agree that the speed of the meteor was 30,000-40,000 miles per hour, which is pretty much the going rate for meteors. That works out to about 15,000 meters per second. The kinetic energy of a moving object is 1/2 times the mass times the velocity squared. For this rough calculation we can ignore the 1/2 (we're looking at a two-order-of-magnitude discrepancy here). So a ten ton (10,000 kg) meteor moving at 15,000 m/s has an energy of about 10^12 Joules. That's less than one kiloton of TNT, not nearly enough to cause the kind of widespread damage that was reported.
So the 7000-10,000 ton figure is almost certainly the correct one.