Are all electric guitar pickups the same size?

No, electric guitar pickups come in different sizes. The most common sizes are single-coil and humbucker. Single-coil pickups are typically around 70mm long and 18mm wide, while humbuckers are typically around 90mm long and 38mm wide. There are also other less common sizes, such as P-90 pickups, which are typically around 85mm long and 28mm wide.