how to Calculate the droplet?

Hi! You can use the List all Droplets API action to get the amount of your Droplets that you have. The response has a meta object that has a total key that should be what you want. Keep in mind though that it’s the amount of all Droplets under your account, not just those created via the API.

{
  "droplets": [
    ...
  ],
  "links": {
    ...
  },
  "meta": {
    "total": 3
  }
}