Like most collectibles, the value of a Zippo lighter is often affected by when it was made. On the bottom of every Zippo windproof lighter, you can find important information that will help you figure out when it was made. Starting in the middle of the 1950s, every Zippo lighter had a date code stamped on the bottom. The original goal was to make sure the quality was good. Since then, the date code has become a very useful tool for people who collect Zippo lighters. Most lighters made between 1933 and 1957 can be identified by their style, model, and the marks that say "patent" or "patent pending.”

The purpose of this guide is not to serve as an authoritative work. It is, rather, designed for people who, when they come across such treasures, would like to date and identify them. People like you and me fall into this category.