Dynamic

Only the sum aggregation type is compatible with the dynamic charge model. If you have a different use case, please reach out to the Lago team for assistance.

Select the dynamic charge model if you calculate the price manually or if prices fluctuate during a billing period (e.g., for SMS APIs, AI models, etc.), and you want to apply a specific total amount per event using the property precise_total_amount_cents. Let’s take the example of our AI company. You may want to charge a custom price per event. Consider the following list of events:

Table view
Events payload

Event	Metric	Unit	Total amount
Transaction 1	Dedicated Instance	7	$0.70
Transaction 2	Dedicated Instance	5	$0.55
Transaction 3	Dedicated Instance	10	$2.20

{
  "events": [
    {
      "transaction_id": "transaction_1",
      "external_subscription_id": "123456789",
      "code": "dedicated_instance",
      "timestamp": 1728554400,
      "precise_total_amount_cents": "70", //event total amount
      "properties": {
        "unit": "7"
      }
    },
    {
      "transaction_id": "transaction_2",
      "external_subscription_id": "123456789",
      "code": "dedicated_instance",
      "timestamp": 1728558000,
      "precise_total_amount_cents": "55", //event total amount
      "properties": {
        "unit": "5"
      }
    },
    {
      "transaction_id": "transaction_3",
      "external_subscription_id": "123456789",
      "code": "dedicated_instance",
      "timestamp": 1728561600,
      "precise_total_amount_cents": "220", //event total amount
      "properties": {
        "unit": "10"
      }
    }
  ]
}'

At the end of the period, the invoice will generate one fee of $3.435 (see example below).

Item	Unit	Unit price	Amount
Dedicated Instance	22	$0,156818	$3.45

To display more detailed information on fees, please refer to the custom invoice grouping or the pay in advance option.

Only the standard & dynamic charge models support the custom invoice grouping.

Graduated percentage Custom price

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Introduction

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Events & Usage Components

Pricing & Subscriptions

Invoicing

Payments & Cash Collection

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