Pizza is named after its diameter, such as a 9-inch pizza, which means that the diameter of a pizza is 9 inches, and 1 inch is 2.54 cm, so if you want to convert it into centimeters, you only need to multiply the diameter of an inch by 2.54 to get that a 9-inch pizza is 22.86 cm.
Extended data:
The origin of pizza:
Pizza comes from bread, which has played an important role as a staple food in western history. It is not always static in the long river of time, but by adding different ingredients to better meet people's needs and hobbies.
Historians found a similar transitional food from bread to pizza in Sardinia, Italy, 3000 years ago. Pie bread in ancient Greece πλακο (plakous, and π λ α κ ο? ντο? -plakountos) Add various spices, including garlic and onion.
And Persians, a king named Dario Il Grande (521-486A.C.) baked a' flat bag' with stones, and added cheese.
There is also the earliest transition in the western poem Enidede, which is generally called "focaccia" (meaning baked with fire), "coca" (both salty and sweet), "pita" in Greek and Italian or "pide" in Turkish, and "piadina" in Romagne. Then other countries have similar food.
Time goes by slowly, and language is not static. Italian pita /pitta has gradually become pizza, and the ingredients on it are no longer limited to the original ones. The innovation of pizza still comes from the addition of tomatoes (in fact, there is a kind of fish that is replaced in the position of tomatoes). Naples first brought this change, which can be said to be the origin of modern pizza.
But in the end, it was a Neapolitan chef who made a pizza margarita specially for Queen Seville at 1889 and named it after the Queen.
References:
Baidu Baike-Pizza (Gourmet)