This topic describes the instance types, free monthly quota, billable items, unit prices, and benefits of Function Compute and provides examples on how Function Compute is billed.

Instance types

Function Compute provides the following instance types:

  • Flexible instance: the basic instance type of Function Compute. The maximum package size for a flexible instance is 50 MB. The execution duration of functions by a flexible instance is up to 900 seconds.
  • Performance instance: an instance type that has higher specifications. Function Compute provides multiple specifications with higher resource limits for performance instances. Therefore, performance instances are applicable to more scenarios than flexible instances.

For more information, see Instance specifications and usage modes.

Free monthly quota

Function Compute provides you with the free monthly quota. Your Alibaba Cloud account and RAM users share the free monthly quota of requests and execution duration of functions. The free monthly quota does not accumulate. At 00:00:00 on the first day of each calendar month, the free quota is cleared and recalculated. The following resources are included in the free monthly quota:

Notice The free monthly quota can be used only for pay-as-you-go flexible instances.
  • Requests: The first one million requests each month are free of charge.
  • Resources for function executions: The first 400,000 GB-s of resources used by instances each month are free of charge.

Billable items and unit prices

Function invocation fees = Number of requests x Unit price
Unit price: USD 0.2 per 1,000,000 requests
Fees for resource usage of instances = Computing power of instances × Execution duration × Unit price
  • Computing power of instances: The computing power of an instance is proportional to the memory size allocated to the instance. To simplify the billing model, Function Compute uses the memory size of an instance to indicate the computing power of the instance.
  • Execution duration: Instances can be used in provisioned or on-demand mode. The execution duration of functions by provisioned instances and that by on-demand instances are measured in different ways. For more information, see Instance specifications and usage modes.

Note:
  • Function Compute provides computing capabilities that match those of Elastic Compute Service (ECS) and Container Service for Kubernetes. You do not need to worry about the computing power of instances.
  • Function Compute allows you to concurrently process requests by using a single instance. Reused resources are billed based on the amount of resources that are used and are not repeatedly billed for each reuse.
Unit price
The resource usage of instances is billed in the following two methods:
  • Subscription: Purchase a specific number of resource coupons based on the estimated requirements before you use Function Compute.
    Unit price: USD 12.16 per GB per month. This is the monthly fee for an instance that has 1 GB of computing power.
  • Pay-as-you-go: Pay for the resources that are used.
    Unit price: USD 0.000016384 per GB per second. This is the fee for an instance that has 1 GB of computing power to execute requests for 1 second.

Note:
  • When you purchase resource coupons, no instances are created.
  • Resource coupons can be used to offset the fees for both provisioned and on-demand instances. If Function Compute fails to deliver the resources that you purchased due to insufficient underlying computing resources, you can be reimbursed for the fees for the undelivered resources. We recommend that you create provisioned instances and purchase resource coupons to offset the fees for the instances.
  • For more information about how to minimize the costs in subscription mode, see Best practices of minimizing Function Compute costs.
Fees for outbound Internet traffic = Traffic within a function × Traffic unit price + Traffic for responses to requests × Traffic unit price + CDN back-to-origin traffic × Traffic unit price
  • Traffic within a function: the traffic generated when the function sends requests to the Internet.
    Unit price: USD 0.117 per GB
  • Traffic for responses to requests: the traffic generated when the function sends responses to requests.
    Unit price: USD 0.117 per GB
  • CDN back-to-origin traffic: the traffic generated when the function is used as the origin of Alibaba Cloud CDN.
    Unit price: USD 0.117 per GB

Note:
  • Traffic over the internal network is free of charge.
  • Inbound Internet traffic is free of charge. For example, you are not charged when functions in Function Compute read or download files from the Internet. However, you are charged for the traffic generated when functions write files to storage objects on the Internet.
If you use other Alibaba Cloud services together with your functions, additional fees are charged for these services. For example, if you use a function to write data to Object Storage Service (OSS) or activate Log Service to store the logs of your functions, additional fees for OSS or Log Service are charged.

Billing examples

The following table describes how to calculate the monthly fee for a pay-as-you-go instance.

Memory size Number of requests Execution duration per request Network bandwidth Monthly fee
512 MB 3 million 1 second 0 USD 18.4224 = (512 MB/1024 × 3,000,000 × 1 second - 400,000 GB-s) × USD 0.000016384/GB-s + (3,000,000 - 1,000,000) × USD 0.2/1,000,000
128 MB 30 million 200 milliseconds 0 USD 11.5344 = (128 MB/1024 × 30,000,000 × 0.2 seconds - 400,000 GB-s) × USD 0.000016384/GB-s + (30,000,000 - 1,000,000) × USD 0.2/1,000,000
128 MB 25 million 200 milliseconds 0 USD 8.4864 = (128 MB/1024 × 25,000,000 × 0.2 seconds - 400,000 GB-s) × USD 0.000016384/GB-s + (25,000,000 - 1,000,000) × USD 0.2/1,000,000
448 MB 5 million 500 milliseconds 0 USD 12.1664 = (448 MB/1024 × 5,000,000 × 0.5 seconds - 400,000 GB-s) × USD 0.000016384/GB-s + (5,000,000 - 1,000,000) × USD 0.2/1,000,000
1024 MB 2.5 million 1 second 0 USD 34.7064 = (1024 MB/1024 × 2,500,000 × 1 second - 400,000 GB-s) × USD 0.000016384/GB-s + (2,500,000 - 1,000,000) × USD 0.2/1,000,000

Benefits

Function Compute allows you to concurrently process requests by using a single instance and charges you for the resource usage of the instance. You can reduce costs by reusing resources to process a large number of requests.

Assume that you want to process 1,000,000 requests and 1 second is required to process each request. The following table compares the fee for a single instance that processes a single request at a time and fee for a single instance that concurrently processes multiple requests.
Usage mode Fee for 1,000,000 requests
A single instance that processes a single request at a time Resource usage fee = 1,000,000 × 1 second × USD 0.000016384/GB-s= USD 16.384
A single instance that concurrently processes multiple requests Assume that the instance can concurrently process 10 requests.

Resource usage fee = 1,000,000 × 1 second/10 × USD 0.000016384/GB-s = USD 1.6384

Billing information

For the detailed billing information, see the following topics: