I believe they are not able to be accurately weighed due to inconsistent amounts of glue that throw off the weights. This is all assuming you are trying to weigh for holos. If you just want to know the weight of the item then I’m sure someone in here has some they can weigh for you!
If you’re attempting to find out if heavy for holo, what I’ve seen from someone who opened a Blister Pack do. If you look at the booster pack at a angle your able to somewhat tell if the pack has a bow in it. I’ve only seen this theory attempted once and a Holo was pulled. But it could also be because the cardboard isn’t flat