A function for Google Sheets that automatically fetches the number of subscribers that a subreddit has. Simply pass in the name of the subreddit.

getSubredditSubscribers.js

// Installation: On a Google Sheet, go to Tools > Script Editor and paste the code into the resulting editor.
// Save and return to your editor and use as follows:

// Usage: getSubredditSubscribers("funny")

// Supports subreddits in the following forms:
// programming
// http://www.reddit.com/r/electronics

//Refresh key can be used for force a refresh by including an arbitrary number 

function getSubredditSubscribers(input,refreshkey) {
    if (input == undefined) {
    input = ["babyelephantgifs"];
    Logger.log("debug mode");
  }
  if (!Array.isArray(input)) {
    input = [input];
  }
  var retarray = [];
  for (var i=0; i<input.length; i++) {
    var subreddit = input[i];
    var url = subreddit;
    if (!subreddit.indexOf("http") == 0) {
      url = "https://www.reddit.com/r/"+subreddit;
    }
    if (url[url.length-1] == "/") url = url.substring(0,url.length-1);
    url = url + "/about.json";
    var content = UrlFetchApp.fetch(url).getContentText();
    var data = JSON.parse(content);
    var subscribers = data['data']['subscribers'];
    retarray.push(subscribers);
  }
  Logger.log(retarray);
  return retarray.length == 1 ? retarray[0] : retarray;
}