Untitled

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public static class CameraExtension
{
    public static float UnitsPerPixel(this Camera cam)
    {
        var p1 = cam.ScreenToWorldPoint(Vector3.zero);
        var p2 = cam.ScreenToWorldPoint(Vector3.right);
        return Vector3.Distance(p1, p2);
    }

    public static float PixelsPerUnit(this Camera cam)
    {
        return 1 / UnitsPerPixel(cam);
    }
}