Usually, when you fill something, it becomes heavier. However, with USB sticks, it seems to be the opposite. Here's why an empty USB stick is heavier than a full one.
Why empty USB sticks are heavier than full ones The more files you write to your USB stick, the lighter it becomes. USB sticks are made of so-called flash memory, which stores data as ones and zeroes using transistors. An empty USB stick contains almost only zeroes. In contrast, a filled USB stick contains both zeroes and ones. But the zeroes are "heavier," and here's why:
To store a "0" on the USB stick, a voltage is applied. To store a "1", the voltage is removed. Adding electrons creates a voltage. An electron weighs 0.00000000000000000000000000091 g. So, an empty USB stick, which consists mostly of zeroes, is heavier than a filled USB stick that contains "zeros" and "ones" because, electronically speaking, the "ones" weigh nothing.
By the way, most flash memory manufacturers indicate a durability of about 10 years. Your USB stick should therefore last that long before read or write errors occur.
Why you can't weigh the difference
The weight of an electron mentioned above is so small that even a precision scale cannot detect the difference between a full and an empty USB stick. To do so, you would need a very precise scale that can display 20 to 30 decimal places.
We know what we're talking about: we weighed an empty USB stick, then wrote it full and weighed it again. The result showed no weight difference.
If you want to buy a new USB stick, we recommend those with at least 256 GB of storage space. This gives you enough space for your files, movies, photos, and music:
Assessment and criticism
We want to mention that there are conflicting pieces of information on this topic:
In other explanations, you can find the opposite argumentation that an empty USB stick is instead lighter than a full one. According to the functionality of a USB stick mentioned above, however, the explanation that an empty USB stick is heavier makes sense. Ultimately, you would need a very precise scale and several experiments with USB sticks to confirm this. We don't have such a scale ourselves.