Is there a dress code to see the statue of David?
No. The Galleria dell'Accademia di Firenze, the museum in Florence, Italy that houses Michelangelo's Statue of David, does not enforce a formal dress code. The published rules forbid only swimsuits, skimpy clothing, walking barefoot, and walking shirtless inside the galleries. Florence's churches, including the Duomo, do enforce a strict shoulders-and-knees rule, and that church requirement is what most visitors confuse with the museum's.
What the official museum rules say?
The Accademia lists a single sartorial restriction in its access rules. Visitors are forbidden to wear clothes inappropriate to the decorum of the place, with swimsuits and skimpy clothes named explicitly. Walking barefoot or shirtless inside the galleries is also prohibited. The rules name no positive prescription about coverage, fabric, or length, so jeans, shorts, sundresses, T-shirts, and tank tops are all fine in practice.
Beyond clothing, the rules also prohibit flash photography, selfie sticks, large tripods, drones, food and drinks other than water in plastic bottles up to 0.5 litres, umbrellas that do not close, and smoking, including e-cigarettes. Mobile phones must be off or on silent.
Florence churches are different?
The dress-code confusion comes from the city's churches, not the Accademia. Florence Cathedral (the Duomo), Santa Maria Novella, Santa Croce, and San Lorenzo all enforce a coverage rule. Shoulders and knees must be covered, including in summer, and staff turn visitors away at the door.
For visitors combining David with a church on the same day, a light scarf or shawl that covers the shoulders, plus trousers or a knee-length skirt, will clear both checkpoints without a wardrobe change.
Bag size and security at the entrance
Anything brought into the Accademia passes through a metal detector. Knives and other items judged dangerous are confiscated and held during the visit. Bags are limited to a maximum of 40 by 30 by 18 centimetres; luggage, large backpacks, helmets, and bulkier items are not admitted, and the museum does not run a cloakroom. Plan for a small day bag and store anything larger before arrival. To make your entrance as smooth as possible, we highly recommend booking a skip-the-line ticket for the David in advance.