The billing of Elastic Compute Service (ECS) instance types refers to the billing of computing resources (vCPUs and memory). This topic describes the billing methods of instance types, comparison of these billing methods, and how to choose billing methods based on scenarios.
Overview
Instance types are billed based on computing resources, including vCPUs and memory.
Prices of an instance type may vary with regions. For more information, see the Pricing tab on the Elastic Compute Service page.
Note If you select an instance type that is equipped with local disks, the price of the
instance type includes that of local disks.
Billing methods
The following table describes the billing methods of instance types.
| Billing method | Description | References |
|---|---|---|
| Subscription |
A billing method that allows you to use instance types only after you pay for them. Price = Unit price of an instance type × Subscription duration. |
Subscription |
| Pay-as-you-go |
A billing method that allows you to use instance types before you pay for them. Price = Unit price of an instance type × Billing duration. The billing cycle is accurate to the second. |
Pay-as-you-go |
| Preemptible instance | Preemptible instances are on-demand instances that you can use before you pay for them. Preemptible instances offer some discounts compared with pay-as-you-go instances and are charged based on the actual usage duration. Prices of preemptible instances fluctuate based on the changes to supply and demand. | Preemptible instances |
| Reserved instance |
Reserved instances are coupons that must be used together with pay-as-you-go instances. Compared with pay-as-you-go instances, reserved instances offer some discounts. Prices of reserved instances are determined based on the region, instance type, operating system, payment option, term, and instance quantity. Reserved instances are used to offset the bills of pay-as-you-go instances based on the resources that you specified when you purchased the reserved instances. Reserved instances can be applied only when they are matched to pay-as-you-go instances. |
Reserved instances |
| Savings plan | Savings plans are discount plans that are used together with pay-as-you-go instances and provide billing discounts on the pay-as-you-go instances in exchange for a usage commitment. Prices of savings plans are determined based on the hourly commitment, payment method, and subscription duration. After you purchase savings plans, the pay-as-you-go billing discounts that you can obtain are determined based on the selected savings plan type, payment option, subscription duration, and attributes of matched pay-as-you-go instances such as regions and instance types. Savings plans are used to offset the bills of pay-as-you-go instances based on the usage commitment and are not restricted by regions or instance families. | Savings plans |
Note You can purchase reserved instances and savings plans at the same time. Reserved instances
take precedence over savings plans to offset the bills of pay-as-you-go instances.
Comparison of billing methods
The following table describes the comparison of billing methods.
| Item | Subscription | Pay-as-you-go | Preemptible instance | Reserved instance | Savings plan |
|---|---|---|---|---|---|
| Usage | All operations are linked to the purchased instance. | All operations are linked to the purchased instance. | All operations are linked to the purchased instance. | Resources are decoupled from bills. Reserved instances must be used together with pay-as-you-go instances. | Resources are decoupled from bills. Savings plans must be used together with pay-as-you-go instances. |
| Payment option | You make a full payment for instance types before you use them. | You pay for instance types after you use them. The instance types are charged by second and billed by hour. | You pay for instance types after you use them. The instance types are charged by second and billed by hour. | You can choose All Upfront, Partial Upfront, or No Upfront. | You can choose All Upfront, Partial Upfront, or No Upfront. |
| Price feature | Subscription instances are more cost-effective than pay-as-you-go instances. | Pay-as-you-go instances are the least cost-effective. | Prices of preemptible instances fluctuate based on the changes to supply and demand. The discounts can be up to 90% of pay-as-you-go prices. | Compared with pay-as-you-go instances, reserved instances offer some discounts. The discounted prices are close to those of subscription instances. | Savings plans offer some discounts and are more flexible compared with pay-as-you-go instances, but come with slightly higher prices than reserved instances. |
| Instance release | You can manually release instances or they can be released by the system. If you want to release an instance before it expires, you must unsubscribe from the instance or change its billing method to pay-as-you-go. If you do not renew an instance within the required period of time after it expires, the instance is automatically released. | You can release instances at any time. | You can manually release instances or they can be released by the system. Preemptible instances can be reclaimed and may be automatically released after the protection period ends. | Reserved instances must be used together with pay-as-you-go instances. Pay-as-you-go instances that match reserved instances can be released at any time. After the pay-as-you-go instances are released, the reserved instances can be used to match and offset the bills of new pay-as-you-go instances. | Savings plans must be used together with pay-as-you-go instances. Pay-as-you-go instances that match savings plans can be released at any time. After the pay-as-you-go instances are released, the savings plans can be used to match and offset the bills of new pay-as-you-go instances. |
| Scenario | Subscription instances are applicable to services that run for 24 hours a day and seven days a week, such as web services and databases. | Pay-as-you-go instances are applicable to services that experience traffic spikes, such as temporary scaling, interim testing, and scientific computing. | Preemptible instances are applicable to services that experience traffic spikes, such as temporary scaling, interim testing, and scientific computing. | Reserved instances are used to match and offset the bills of pay-as-you-go instances, and are applicable to web services and databases. | Savings plans are used to match and offset the bills of pay-as-you-go instances, and are applicable to web services and databases. |
You can choose appropriate billing methods for ECS instances on which different applications
are deployed to reduce costs. The following figure shows the recommended combinations
of billing methods. 
For stable business loads, you can use the subscription billing method and reserved
instances or savings plans to obtain some discounts. When ECS instances have the same
subscription duration, savings plans are the most flexible, and reserved instances
are more flexible than subscription. The following table describes the comparison
between subscription, reserved instances, and savings plans.
| Feature | Subscription | Reserved instance | Savings plan |
|---|---|---|---|
| Discount limits | Discounts are offered only for a single instance. | A reserved instance can match a maximum of 100 specified pay-as-you-go instances to offer discounts. | Savings plans are used to offset bills without limits on the number of instances. Savings plans are flexible. |
| Resource reservation | Supported. | Supported. You must use zonal reserved instances. | Not supported. |
| Use across services | Not supported. | Supported. Reserved instances can be used in ECS and Elastic Container Instance. | Supported. Savings plans can be used in ECS and Elastic Container Instance. |
| Use across regions | Not supported. | Not supported. | Supported. General-purpose savings plans can be used across regions. |
| Use across zones in the same region | Not supported. | Supported. You must use regional reserved instances. | Supported. |
| Use across instance families | Not supported. | Not supported. | Supported. General-purpose savings plans can be used across instance families. |
| Use across instance types in the same instance family | Not supported. | Supported. | Supported. |
| Use across operating systems | Not supported. | Not supported. | Supported. |
| Use across accounts (based on the established trusteeship) | Not supported. | Supported. | Supported. |
| Installment | Not supported. | Supported. You can choose All Upfront, Partial Upfront, or No Upfront. | Supported. You can choose All Upfront, Partial Upfront, or No Upfront. |
Examples of typical scenarios
The following figure shows some typical scenarios to which you can refer to choose
appropriate billing methods. 
| Business type | Linked pattern | Stable pattern | Burstable pattern | Hybrid pattern |
|---|---|---|---|---|
| Business characteristic | All business segments are closely linked. When traffic loads of one business segment increase, traffic loads of other business segments also increase. | Business loads are stable with no obvious peak hours or off-peak hours. | All business segments are loosely linked. Business loads may become burstable at some points in time. | A variety of business segments exist. Each business segment has a unique requirement for computing power during a specific time period. The business segments have different priorities. |
| Example scenario | Hot issues, e-commerce promotions, and traffic spikes of IoT. | Stable online business, such as internal office automation (OA) systems. | Event-based tasks, job tasks, and simulation tasks. | Scenarios where online, offline, and job tasks are deployed in a hybrid manner and where multiple environments are used alternately, such as blue-green deployment. |
| Recommended billing method | Pay-as-you-go and savings plans (or reserved instances). |
|
Pay-as-you-go.
You can combine the pay-as-you-go billing method with savings plans or reserved instances if traffic bursts frequently occur. |
Pay-as-you-go and savings plans (or reserved instances). |
References
You can change the billing method of an instance from subscription to pay-as-you-go
or from pay-as-you-go to subscription.
- For information about how to change the billing method of an instance from subscription to pay-as-you-go, see Change the billing method of an instance from subscription to pay-as-you-go.
- For information about how to change the billing method of an instance from pay-as-you-go to subscription, see Change the billing method of an instance from pay-as-you-go to subscription.