Flag tanning stickers are a great way to measure your tan. It is always hard to see your own tanning progress by looking in the mirror. Tanning is a somewhat gradual process and therefore your color changes throughout the day and from one day to the next. The only effective way to effectively measure your tanning progress is to use a flag tanning sticker in the same spot each time you tan. Almost everyone is surprised by how tan they actually are once they have used a flag sticker for a few weeks.