When it comes to frozen shrimp, skip weighing them: count out what you need instead.
Frozen shrimp are individually encased in icy shells that add weight, so if a recipe calls for 8 ounces of shrimp, should you defrost some extra to allow for the weight that will be lost when the ice melts? If so, how much?
Attempting to find a useful rule of thumb, we weighed out seven batches of frozen shrimp (testing across brands, sizes, and peeled versus unpeeled) and weighed them again after they were thawed and drained. We found that the thawed shrimp were 12 to 25 percent lighter and that a batch of smaller shrimp had proportionately more loss due to its greater surface area.
Our advice? When it comes to frozen shrimp, skip weighing them. Instead, note that in addition to being labeled small, medium, large, etc., shrimp are labeled with the range of pieces per pound, such as 26/30 for large shrimp. This number (which is clearly marked on the packaging) represents raw, unfrozen weight, so if your recipe calls for 8 ounces of large shrimp, simply count out 15 shrimp—half of the top of the range. That way you’ll be sure to have enough post-thaw.