Overview

There are yearly/monthly and pay-per-use billing modes. Each one has different advantages and disadvantages.

Yearly/Monthly is a prepaid billing. You pay in advance for a subscription term, and in exchange, you get a discounted rate. The longer the subscription period, the higher the discount.
Pay-per-use is a postpaid billing mode. You pay as you go and just pay for what you use. A pay-per-use EIP can be billed by traffic or by bandwidth.

Table 1 describes the application scenarios of different billing options.

**Table 1** Application scenarios of EIP billing options
Billing Mode	Billed By	Application Scenario
Yearly/Monthly	Bandwidth	For heavy/stable traffic For predictable usage period
Pay-per-use	Bandwidth	For heavy/stable traffic For temporary and urgent-purpose usage
	Traffic	For light or sharply fluctuating traffic For temporary and urgent-purpose usage
	Shared bandwidth	For light or sharply fluctuating traffic

For details about EIP billing, see Figure 1 and Table 2.

Figure 1 EIP billing

**Table 2** Differences between billing modes
Billing Mode	Yearly/Monthly	Pay-per-use (Billed by bandwidth)	Pay-per-use (Billed by traffic)	Pay-per-use (Shared bandwidth)
Payment	Prepaid Billed by the subscription term you purchase.	Postpaid Billed based on your specified bandwidth size and usage duration. There is no limit on how much traffic you can use.	Postpaid Billed based on your EIP type and the total amount of traffic going out of the cloud.	Postpaid Billed by the shared bandwidth.
Billing Method	Billed by the subscription term you purchase, accurate to seconds.	Calculated by the second but billed every hour	Calculated by the second but billed every hour	Calculated by the second but billed every hour
Billed Items	Bandwidth	Bandwidth EIP	Traffic EIP	Shared bandwidth EIP
Billed Item Description	If you buy a yearly/monthly EIP, you only need to pay for the bandwidth included in the subscription. You are billed based on your specified bandwidth size and usage duration. There is no limit on how much traffic you can use.	Bandwidth: You are billed based on your specified bandwidth size and usage duration. There is no limit on how much traffic you can use. After an EIP is purchased, you can change your specified bandwidth size. Although the total traffic is unlimited, your available bandwidth is limited to what was specified at the time of purchase. EIP: If an EIP is not released, it will continue to be billed even if it is not bound to an instance.	Traffic: You are billed based on your EIP type and the total amount of traffic going out of the cloud. The bandwidth size you set is only used to limit the maximum data transfer rate. To prevent high fees caused by traffic bursts, specify a proper bandwidth size when you buy an EIP. EIP: If an EIP is not released, it will continue to be billed even if it is not bound to an instance.	If a pay-per-use EIP is added to a shared bandwidth: Share bandwidth: Only the shared bandwidth will be billed. There will be no additional bandwidth or traffic costs for EIPs added to the shared bandwidth. EIP: If an EIP is not released, it will continue to be billed even if it is not bound to an instance.
Changing the Billing Mode	Yearly/Monthly can be changed to pay-per-use (by bandwidth). For details, see Yearly/Monthly to Pay-Per-Use.	Pay-per-use can be changed to yearly/monthly. The new billing mode is applied immediately. For details, see Pay-per-Use to Yearly/Monthly.	An EIP that is billed by traffic on a pay-per-use basis cannot be directly changed to be billed on a yearly/monthly basis. You need to change the EIP to be billed by bandwidth on a pay-per-use basis first, and then change the EIP to be billed on a yearly/monthly basis. The new billing mode is applied immediately. For details, see Pay-per-Use to Yearly/Monthly.	The billing mode cannot be changed.
Changing Specifications	Bandwidth can be increased or decreased.	Bandwidth can be increased or decreased.	Bandwidth can be increased or decreased. The bandwidth size you set is only used to limit the maximum data transfer rate.	Bandwidth can be increased or decreased.

Cloud Eye monitors your network metrics, such as bandwidth and traffic. Based on the bandwidth usage, you can determine which billing option (by bandwidth or by traffic) is more cost-effective. Here are some suggestions for your reference:

If you need less than 5 Mbit/s of bandwidth, set your EIP to be billed by bandwidth on a pay-per-use basis, or choose yearly/monthly depending on how long you will need the bandwidth for.
If you need more than 5 Mbit/s of bandwidth and the bandwidth usage is greater than 20%, set your EIP to be billed by bandwidth.
If you need a bandwidth of 5 Mbit/s, select either billing mode.
For details, see Viewing Metrics.

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