Conversions
// Inches → Centimetres cm = inches × 2.54 // Centimetres → Inches inches = cm ÷ 2.54 // Pizza & baking pan reference Inches cm Common Italian description 6" 15.2 cm Small dessert / single-serve 8" 20.3 cm Piccola torta (20 cm) 9" 22.9 cm Torta standard (24 cm Italian equiv) 10" 25.4 cm Crostata / tart (26 cm) 12" 30.5 cm Pizza standard (30 cm) 13" 33.0 cm Pizza grande 14" 35.6 cm Max pizza napoletana (35 cm spec) 18"×13" 46×33 cm Half-sheet / teglia da forno
A 12-inch pizza has a diameter of 30.48 cm, typically quoted as 30 cm in Italian menus. A standard Neapolitan pizza is slightly smaller at 28–33 cm diameter.
A 9-inch cake tin = 22.86 cm, typically rounded to 23 cm. The equivalent Italian size is a 24 cm springform tin (tortiera), which is the most common size in Italian baking.
Italy uses the metric system, so all bakeware, pan sizes, and kitchen equipment are sold and described in centimetres. American recipes specify pan sizes in inches. When adapting US recipes for Italian kitchens (or ordering equipment), conversion is necessary.
Most Italian restaurants serve individual pizzas of 28–33 cm (11–13 inches) in diameter. The Associazione Verace Pizza Napoletana specifies a maximum diameter of 35 cm for certified Neapolitan pizza.
When scaling a recipe between pan sizes, the key factor is area: area = π × (diameter/2)². If you switch from a 9-inch (23 cm) tin to an 8-inch (20 cm) tin, the area decreases by about 20%, so reduce ingredient quantities accordingly.