Ars calculates the size of the DualShock 4 touchpad: about 2.1” x 1”

A little image wrangling (and math) generates a general sizing estimate.

PlayStation Vita - Wikipedia

upload.wikimedia.org/wikipedia/commons/thumb/a/ac/

ISO 9241-9 Evaluation of Video Game Controllers

DualShock 4 (CUH-ZCT1U) Touch Pad Replacement - iFixit Repair Guide

Smart controller: Introducing a dynamic interface adapted to the gameplay - ScienceDirect

Game Controller Repairing Touch Pad Accessory, Wearable and Durable Replacement Touchpad for PS4 Gamepad : Video Games

Best Buy: Microsoft Surface Pro 8 – 13” Touch Screen – Intel Evo Platform Core i5 – 8GB Memory – 512GB SSD – Device Only Platinum EBP-00001

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How to transfer Dualshock 4 Touchpad Circuit Board - PS4

math Ars Technica