Our holographic stickers are approximately 7.6 mil (195 microns), excluding the paper backing, which is around 2.7 mil (70 microns) thick.
One mil is one-thousandth of an inch. One micron is a millionth of a meter.
To put that thickness into perspective, a thin sticker is around 1.7 mil (45 microns), so they're nice, thick, and durable.
Here is an exploded view of our holographic stickers, showing you each layer: