How to calculate total size of webpage with Google PageSpeed API?

"statistics": {
    "cssResponseBytes": "333 kB",
    "htmlResponseBytes": "269 kB",
    "imageResponseBytes": "3.35 MB",
    "javascriptResponseBytes": "2.29 MB",
    "numberCssResources": 2,
    "numberHosts": 80,
    "numberJsResources": 72,
    "numberResources": 237,
    "numberStaticResources": 50,
    "otherResponseBytes": "53.1 kB",
    "textResponseBytes": "160 kB",
    "totalRequestBytes": "69.7 kB"
  },

This is the JSON response im getting for the statistics of a page from the Google PageSpeed API. How can I calculate the entire download size of loading the page with this, if possible? My assumption is to ADD the first 4 lines in the response together (responsebytes)