Quick guide to ad group budget distribution with Google Ads script

function main() {
  // Set to the number of time slots per day to use as a basis for balancing ad groups
  const TIME_SLOTS = 8;
  const TIME_SLOT_DURATION = 24 / TIME_SLOTS; // Hours per slot

  // Define a minimum bid to prevent excessively low values
  const MIN_BID = 0.5; // Adjust based on your market

  // Get current time and determine the active time slot
  const now = new Date();
  const currentHour = now.getHours();
  const currentSlot = Math.floor(currentHour / TIME_SLOT_DURATION); // 0-indexed slot

  Logger.log(`Current time slot: ${currentSlot + 1}/${TIME_SLOTS}`);

  // Fetch all enabled campaigns
  const campaigns = AdsApp.campaigns()
    .withCondition("Status = ENABLED")
    .get();

  while (campaigns.hasNext()) {
    const campaign = campaigns.next();

    // Get the campaign's daily budget dynamically
    const campaignBudget = campaign.getBudget().getAmount();
    const timeSlotBudget = campaignBudget / TIME_SLOTS; // Allocate evenly across time slots

    Logger.log(
      `Campaign "${campaign.getName()}" has a daily budget of ${campaignBudget}. Allocating ${timeSlotBudget} for this time slot.`
    );

    // Fetch all enabled ad groups within the campaign
    const adGroups = campaign.adGroups()
      .withCondition("Status = ENABLED")
      .get();

    const activeAdGroupsCount = adGroups.totalNumEntities();
    if (activeAdGroupsCount === 0) continue;

    // Calculate the budget per ad group for the current time slot
    const adGroupBudget = timeSlotBudget / activeAdGroupsCount;

    while (adGroups.hasNext()) {
      const adGroup = adGroups.next();

      // Fetch today's spend for the ad group
      const stats = adGroup.getStatsFor("TODAY");
      const spendSoFar = stats.getCost();

      // Calculate remaining budget for the ad group in this slot
      const remainingBudget = adGroupBudget - spendSoFar;

      // Fetch historical performance data for the ad group
      const historicalStats = adGroup.getStatsFor("LAST_7_DAYS");
      const averageCpc = historicalStats.getAverageCpc();

      // Fetch current CPC bid
      const currentCpc = adGroup.bidding().getCpc();

      // Determine a new bid based on performance and remaining budget
      let newBid = currentCpc;
      if (remainingBudget > 0) {
        // Increase bid to encourage more spend, considering historical CPC and a minimum bid
        newBid = Math.max(currentCpc * 1.2, averageCpc, MIN_BID);
      } else {
        // Decrease bid to slow down spend
        newBid = Math.max(currentCpc * 0.8, MIN_BID);
      }

      // Update the ad group CPC bid
      adGroup.bidding().setCpc(newBid);

      Logger.log(
        `Adjusted bid for ad group "${adGroup.getName()}" to ${newBid}.`
      );
    }
  }
}

Watch out! This is going to modify all active campaigns. Preview and run in a safe area if you are unsure of what will happen. The script can be modified to pick up only some campaigns, of course, for example:

function main() {
  const remarketingCampaigns = AdsApp.campaigns()
    .withCondition("Name CONTAINS 'Remarketing'")
    .withCondition("Status = ENABLED") // Optional: Fetch only active campaigns
    .get();

  while (remarketingCampaigns.hasNext()) {
    const campaign = remarketingCampaigns.next();
    Logger.log(`Remarketing Campaign: ${campaign.getName()}`);
  }
}