Stud

A stud is the cylindrical bump on top of a LEGO part. It's the connector that makes the whole LEGO magic possible: a stud snaps into the cavity on the bottom of another part with ~10 micrometre precision ("clutch power").

Specs

• Diameter: 4.8 mm (since 1958)
• Height: 1.8 mm
• Centre-to-centre spacing: 8 mm (one stud wide = 8 mm)
• A 1×1 brick = 8×8 mm footprint

In measurements

AFOLs measure in studs, not millimetres. "A 32×32 baseplate" = 256×256 mm. "A modular façade 32 studs wide" = 25.6 cm. Designing a MOC, the stud grid gives you anchor points — almost everything in LEGO is a multiple of 8 mm.

Anti-stud

The anti-stud is the cavity on the bottom of a brick where another stud fits. Usually ring-shaped with a central tube for extra grip on 2×n bricks. 1×1 parts lack that tube — that's why 1×1 clutches less firmly than larger parts.