This topic describes the fees involved for changing the specifications of an ApsaraDB for RDS instance.

## Pay-as-you-go

Pay-as-you-go instances are billed on an hourly basis. After the specifications of a pay-as-you-go instance change, the instance is billed at the new price.

## Subscription

Specification change | Billing |
---|---|

Upgrade immediately | Payment = Total fees of the new specifications for the remaining subscription period
(Monthly price of the new specifications/30/24 × Unused hours) - Total fees of the
original specifications for the remaining subscription period (Monthly price of the
original specifications/30/24 × Unused hours).
Example: The monthly price of the new specifications is USD 14,400. The monthly price of the original specifications is USD 7,200. The unused subscription duration is 50 days. The payment is calculated as follows: (14,400/30/24 × 50 × 24) - (7,200/30/24 × 50 × 24) = USD 12,000. |

Downgrade immediately | Refund = Total fees of the original specifications for the remaining subscription
period (Monthly price of the original specifications/30/24 × Unused hours) - Total
fees of the new specifications for the remaining subscription period (Monthly price
of the new specifications/30/24 × Unused hours).
Example: You subscribed to an instance for three months, during which the original specifications are charged USD 3,500. You paid USD 3,000 after using coupons. After two months, the total fees of the original specifications for the remaining month are USD 1,000. The total fees of the new specifications for a month are USD 800. The refund is calculated as follows: 1000 - 800 = USD 200. |

**Note**If you upgrade the specifications of an instance and then downgrade the specifications, you may get fewer refunds in the following two scenarios:

- Discounts used in the upgrade order: If you subscribed to the instance for a year at a 15% discount, you need to pay only USD 850 to enjoy USD 1,000 worth of service. Then, a refund for downgrading the specifications is calculated based on USD 850.
- You used coupons in the upgrade order: When you downgrade the specifications of the instance, the refund of the original specifications is calculated based on the cash you paid, excluding the amount deducted by coupons. However, when you upgrade the specifications of the instance, the fees of the original specifications are calculated based on the unit price of the original specifications, including the amount deducted by coupons.

## Price details

The price of the RDS instance that you want to purchase varies based on the instance configuration, such as the region, instance type, storage capacity that you select. For more information, go to the ApsaraDB RDS buy page.