Overview

There are yearly/monthly, pay-per-use, and spot pricing 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. 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 ECS usage is calculated by the second but billed every hour. Pay-per-use is a good option for scenarios where there are sudden traffic bursts, such as e-commerce promotions.
Spot pricing is a postpaid billing mode. ECS prices are adjusted gradually based on long-term trends in supply and demand for spot instance capacity. The ECS usage is calculated by the second but billed every hour. Spot instances are made available at a discounted rate, but there is a trade-off for that reduced cost. If inventory resources are insufficient or the market price exceeds your expected price, the spot ECS will be reclaimed. Spot pricing applies when you want to drive down cloud costs.
ECSs that use spot pricing are called spot instances. You need to set a maximum price you are willing to pay for a spot instance. The maximum price must be greater than or equal to the market price but less than or equal to the pay-per-use price. If inventory resources are insufficient or the market price rises above your maximum price, the spot instance will be reclaimed.

Table 1 lists the differences between the billing modes.

**Table 1** Differences between billing modes
Billing Mode	Yearly/Monthly	Pay-per-Use	Spot Pricing
Payment	Prepaid Billed by the subscription term you purchase	Postpaid Billed by service duration.	Postpaid Billed at the market price, which varies according to the changes in supply and demand. The start price is the market price when the ECS was purchased. The ECS is then billed at the market price every hour.
Conditions for Purchase	N/A	N/A	You need to set a maximum price you are willing to pay for a spot instance. If your maximum price is greater than or equal to the market price and the inventory resources are sufficient, you will be provisioned with a spot instance. This spot instance will be billed at the current market price. If your maximum price is less than the market price, you will not be provisioned with a spot instance.
Billing Method	Billed by the subscription term you purchase	Calculated by the second but billed every hour	Calculated by the second but billed every hour
Billed Items	Compute resources (vCPUs and memory), images, EVS disks, and EIPs	Compute resources (vCPUs and memory), images, EVS disks, and EIPs	Compute resources (including vCPUs and memory)
Billing for Stopped ECSs	Stopping an ECS has no impact on the billing of a yearly/monthly ECS. ECSs are billed based on the subscription term you purchase.	After a common ECS is stopped, basic resources (vCPUs, memory, image, and GPUs) will not be billed. Other resources (EVS disks, EIPs, and bandwidth) associated with the ECS instance will continue to be billed. After a special ECS instance is stopped, its resources will be retained and continue to be billed. NOTE: Common instances include: Non-bare-metal instances Instances without local disks Instances without FPGA cards Special instances include: BMS instances ECSs attached with local disks, such as disk-intensive ECSs and ultra-high I/O ECSs ECSs with FPGA cards	After a common ECS is stopped, basic resources (vCPUs, memory, image, and GPUs) will not be billed. Other resources (EVS disks, EIPs, and bandwidth) associated with the ECS instance will continue to be billed. After a special ECS instance is stopped, its resources will be retained and continue to be billed. NOTE: Common instances include: Non-bare-metal instances Instances without local disks Instances without FPGA cards Special instances include: BMS instances ECSs attached with local disks, such as disk-intensive ECSs and ultra-high I/O ECSs ECSs with FPGA cards
Changing the Billing Mode	Yearly/Monthly can be changed to pay-per-use. For details, see Yearly/Monthly to Pay-per-Use.	Pay-per-use can be changed to yearly/monthly. For details, see Pay-per-Use to Yearly/Monthly.	Spot pricing cannot be changed to pay-per-use or yearly/monthly.
Changing the Specifications	Supported	Supported	Not supported
System Disk Detachment	Supported	Supported	Not supported
Conditions for Reclaiming	N/A	N/A	The market price is higher than the maximum price you are willing to pay. The inventory resources are insufficient. You release the ECS instances voluntarily.
Application Scenarios	A cost-effective option for scenarios where the resource usage duration is predictable. Recommended for resources expected to be in use long term.	Recommended when the resource demands are likely to fluctuate and you want more flexibility.	Ideal for stateless, cost-sensitive applications that can tolerate interruptions. Not recommended for workloads that need to run for a long time or that require high stability.