qmk_firmware/layouts/default/numpad_4x4/info.json

{
    "keyboard_name": "4x4 number pad layout",
    "url": "",
    "maintainer": "qmk",
    "width": 4,
    "height": 4,
    "layouts": {
        "LAYOUT_numpad_4x4": {
            "layout": [
                {"x":0, "y":0},
                {"x":1, "y":0},
                {"x":2, "y":0},
                {"x":3, "y":0, "h":2},

                {"x":0, "y":1},
                {"x":1, "y":1},
                {"x":2, "y":1},

                {"x":0, "y":2},
                {"x":1, "y":2},
                {"x":2, "y":2},
                {"x":3, "y":2, "h":2},

                {"x":0, "y":3, "w":2},
                {"x":2, "y":3}
            ]
        }
    }
}