Overview

There are two billing modes: yearly/monthly and pay-per-use.

Yearly/Monthly is a prepaid billing mode. You pay in advance for a subscription term, and in exchange, you get a discounted rate. The longer the subscription term, the bigger the discount. Yearly/Monthly billing is a good option for long-term, stable services.
Pay-per-use is a postpaid billing mode. You pay as you go and just pay for what you use. The instance usage is calculated by the second but billed every hour. Pay-per-use billing is a good option for scenarios where there are sudden traffic bursts, such as e-commerce promotions.

Table 1 lists their differences.

**Table 1** Billing modes
Billing Mode	Yearly/Monthly	Pay-per-use
Payment	Prepaid Settled based on the subscription period specified in your order.	Postpaid Settled based on how long you have actually used your instance.
Billing Cycle	Billed based on the subscription period specified in your order.	Pricing is listed on a per-hour basis, and bills are calculated down to the second.
Billing Item	Instance specifications (vCPUs and memory), storage, backup storage, and EIP	Instance specifications (vCPUs and memory), storage, backup storage, and EIP
Billing Mode Change	A yearly/monthly instance can be changed to pay-per-use. The change is applied only after the yearly/monthly instance expires. For details, see Changing a Yearly/Monthly Instance to Pay-per-Use.	A pay-per-use instance can be changed to yearly/monthly. For details, see Changing a Pay-per-Use Instance to Yearly/Monthly.
Specification Change	Supported	Supported
Scenario	If your future usage is predictable, this billing mode is generally less expensive than pay-per-use. Longer subscriptions offer larger discounts.	You are only billed for how long you have actually used your instance. This mode aligns with your scaling needs of compute resources.