Answer by Kasper Fredenslund:
What an interesting question. It falls into the same category as questions about whether a fully charged phone weighs more than a dead one.The simple answer would be, Yes, a full flash-drive weighs more than an empty one, but just how much?Let's remind ourselves about what data really is. Data is 1's and 0's stored on some medium. For flash storage the 1's and 0's are stored by trapping electrons. These electrons have a weight of [math]1/1820[/math] unit which is the equivalent of 1.7×10^(-24) grams.The more data a flash drive stores on it, the more electrons are trapped. For 4GB of data, the difference between full and empty is 10^(-18) grams. For 32GB, it'd be 8 times of that.These calculations were done back in 2011 by University of California at Berkeley professor of computer sciencefor Amazon’s Kindle e-reader, but they’d be applicable to any flash drive.