Jumper

A jumper is a LEGO plate with fewer studs than its dimensions suggest. The two most common:

• 1×2 jumper (design 3794, 15573, 87580): single stud in the centre of a 1×2 plate
• 2×2 jumper (design 87580 and 26604): one or two studs in the centre of a 2×2 plate

Why the missing studs

The whole LEGO system runs on an 8 mm stud grid. Place a 1×1 on a regular plate and it sits exactly 8 mm from its neighbour. Sometimes you DON'T want that — for instance when a window must shift half a stud left, or a minifig must stand on a precise tile half.

A jumper lets you place a part at half-stud offset (4 mm). For scale models, façades and realistic detail, that's the difference between "looks familiar" and "spot-on".

Examples in official sets

• Modulars use jumpers for window frames and façade ornaments
• Speed Champions cars place head- and tail-lights on jumpers
• Star Wars cockpits use jumpers to centre pilots exactly

Effect on MOC design

The existence of jumpers has freed a whole generation of MOC builders. Before 2010 half-stud offset was only achievable via awkward SNOT tricks; since jumpers became common they appear in every modular and every serious MOC.