Updated July 21, 2017 Locate the two numbers on the back of your watch. The top number is your watch’s model number. Find the bottom number. This is the serial number. It generally comprises two letters and four numbers. In some cases, however, it will be three letters and three numbers, or six numbers. Visit Tag Heuer’s website (see Resources) and locate an authorized retailer in your area. Take the watch to your retailer, which will be able to authenticate your watch and tell you how old it is from the serial number. Resources Writer Bio
