> ## Documentation Index
> Fetch the complete documentation index at: https://lago-ftr-wallet-improvements.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Estimate an upcoming fee

> Estimate the fees that would be created after reception of an event for  a billable metric attached to one or multiple pay in advance charges.

<RequestExample>
  ```bash cURL
  LAGO_URL="https://api.getlago.com"
  API_KEY="__YOUR_API_KEY__"

  curl --location --request POST "$LAGO_URL/api/v1/events/estimate_fees" \
  --header "Authorization: Bearer $API_KEY" \
  --header 'Content-Type: application/json' \
  --data-raw '{
        "event": {
            "external_subscription_id": "__YOUR_SUBSCRIPTION_ID__",
            "code": "__BILLABLE_METRIC_CODE__",
            "properties": {
              "custom_field": 12,
            }
        }
    }'
  ```

  ```python Python
  from lago_python_client.models import Event

  event = Event(
    external_subscription_id="__YOUR_SUBSCRIPTION_ID__",
    code="__BILLABLE_METRIC_CODE__",
  )

  client.events.estimate_fees(event)
  ```

  ```ruby Ruby
  require 'lago-ruby-client'

  client = Lago::Api::Client.new({api_key: '__YOUR_API_KEY__'})

  client.events.estimate_fees(
    external_subscription_id: "__YOUR_SUBSCRIPTION_ID__",
    code: "__BILLABLE_METRIC_CODE__",
    properties: {
      custom_field: 12,
    }
  )
  ```

  ```js Javascript
  import { Client, getLagoError } from 'lago-javascript-client';

  const lagoClient = Client('__YOUR_API_KEY__');

  try {
      const { data } = await lagoClient.events.eventEstimateFees(estimateEvent);
  } catch (error) {
      const lagoError = await getLagoError<typeof lagoClient.events.eventEstimateFees>(error);
  }
  ```

  ```go Go
    import "fmt"
    import "github.com/getlago/lago-go-client"

    func main() {
      lagoClient := lago.New().SetApiKey("__YOUR_API_KEY__")

      eventEstimateInput := &lago.EventEstimateFeesInput{
        ExternalSubscriptionID: "__YOUR_SUBSCRIPTION_ID__",
        Code:          "__BILLABLE_METRIC_CODE__",
        Properties: map[string]string{
          "custom_field": "12",
        },
      }

      err := lagoClient.Event().EstimateFees(eventEstimateInput)
      if err != nil {
        // Error is *lago.Error
        panic(err)
      }
    }
  ```

  ```csharp C#
  using System.Collections.Generic;
  using System.Diagnostics;
  using Org.OpenAPITools.Api;
  using Org.OpenAPITools.Client;
  using Org.OpenAPITools.Model;

  namespace Example
  {
    public class CreateEventExample
    {
      public static void Main()
      {
        Configuration.Default.BasePath = "https://api.getlago.com/api/v1";
        // Configure HTTP bearer authorization: bearerAuth
        Configuration.Default.AccessToken = "YOUR_ACCESS_TOKEN";

        var apiInstance = new EventsApi(Configuration.Default);
        // EventEstimateFeesInput | Event estimate payload
        var eventEstimateInput = new EventEstimateFeesInput();

        try
        {
          // Create a new event
          apiInstance.EventEstimateFees(eventEstimateInput);
        }
        catch (ApiException e)
        {
          Debug.Print("Exception when calling EventsApi.EventEstimateFees: " + e.Message );
          Debug.Print("Status Code: "+ e.ErrorCode);
          Debug.Print(e.StackTrace);
        }
      }
    }
  }
  ```

  ```php PHP
  require_once(__DIR__ . '/vendor/autoload.php');

  // Configure Bearer authorization: bearerAuth
  $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToken('YOUR_ACCESS_TOKEN');


  $apiInstance = new OpenAPI\Client\Api\EventsApi(
    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
    // This is optional, `GuzzleHttp\Client` will be used as default.
    new GuzzleHttp\Client(),
    $config
  );
  $event_estimate_input = new \OpenAPI\Client\Model\EventEstimateFeesInput(); // \OpenAPI\Client\Model\EventEstimateFeesInput | Event estimage fees payload

  try {
      $apiInstance->eventEstimateFees($event_input);
  } catch (Exception $e) {
      echo 'Exception when calling EventsApi->eventEstimateFees: ', $e->getMessage(), PHP_EOL;
  }
  ```
</RequestExample>