Wall plates are usually  95mm wide x 70mm thick whatever the gate size.
Wider plates, say 120mm, can be used especially if fitted near a corner or in soft bricks. The wall fixings can be staggered on these which will spread the load. It’s better not to fit wall plates too near brickwork corners if it can be avoided, come back 50mm -75mm if possible.

Hanging Wall plate is the Wall plate that the gate is hung on and hinged from. A pair of gates may have 2 of these if hung between brickwork.

Closing Wall plate is the wall plate that the gate closes onto with the latch keep fitted to it.

• 70mm thick wall plates are generally best as they allow for more room to accommodate hinge plates and bolt/latch keeps.
• 50mm thick wall plates are acceptable, especially on smaller gates, and will give a little more opening width.