Backup storage for RDS SQL Server is billed pay-as-you-go. The first portion of backup storage — determined by your instance's storage size and backup mode — is free. Fees apply only to the excess beyond this free quota. Your bill reflects only the excess, not total backup size. For example, if your free quota is 40 GB and your total backup size is 60 GB, you are billed for 20 GB.
Billable items
Billable item | Billable item code | Associated product | References |
Storage for regular backups | BackupCharged | RDS | |
Storage for cross-region backups | DdrOssStorageSize | RDS | |
Traffic consumed by cross-region backups | NetworkOutDuplicationSize | Database Backup (DBS) | — |
Internet traffic consumed for backup downloads | NetworkOutSize | Database Backup (DBS) |
Billing rules
The billing formula is the same across all backup modes:
Hourly backup fee = (Total backup size − Free quota) × Unit price
Check the total backup size (not storage space usage) in Basic Information > Instance Resources > Backup Usage on the instance details page.
Data and log backups are stored in independent backup storage and do not occupy instance storage space.
The free quota and unit price vary by backup mode, as described in the following sections.
Physical backup
Applies when the backup mode is physical backup and only physical backup files exist in backup storage.
When switching from snapshot backup to physical backup, if the original snapshot backup files have not expired and been deleted, both file types coexist temporarily. During this period, use the billing rules in Coexistence of snapshot and physical backup files.
Parameter | Value |
Total backup size | Sum of all physical backup and log backup sizes |
Free quota | Instance storage space × 50% |
Unit price (cloud disk instances) | 0.00004 USD/GB/hour |
Unit price (local disk instances) | 0.00020 USD/GB/hour |
Example: Cloud disk instance in physical backup mode
Item | Value |
Instance region | China (Hangzhou) |
Instance storage space | 20 GB |
Total backup size | 30 GB (data backup: 20 GB, log backup: 10 GB) |
Unit price | 0.00004 USD/GB/hour |
Calculation:
Free quota = 20 GB × 50% = 10 GB
Excess = 30 GB − 10 GB = 20 GB
Hourly fee = 20 GB × 0.00004 = 0.0008 USD/hour
Snapshot backup
Applies when the backup mode is snapshot backup and only snapshot backup files exist in backup storage.
When switching from physical backup to snapshot backup, if the original physical backup files have not expired and been deleted, both file types coexist temporarily. During this period, use the billing rules in Coexistence of snapshot and physical backup files.
Parameter | Value |
Total backup size | Sum of all snapshot backup and log backup sizes |
Free quota | Instance storage space × 200% |
Unit price | 0.00004 USD/GB/hour |
Example: Cloud disk instance in snapshot backup mode
Item | Value |
Instance region | China (Hangzhou) |
Instance storage space | 20 GB |
Total backup size | 60 GB (data backup: 40 GB, log backup: 20 GB) |
Unit price | 0.00004 USD/GB/hour |
Calculation:
Free quota = 20 GB × 200% = 40 GB
Excess = 60 GB − 40 GB = 20 GB
Hourly fee = 20 GB × 0.00004 = 0.0008 USD/hour
Coexistence of snapshot and physical backup files
Applies during the transition period after switching backup modes, when both backup file types exist in backup storage simultaneously.
Once the older backup files expire and are deleted, only one type remains. Switch to the Physical backup or Snapshot backup billing rules accordingly.
Parameter | Value |
Total backup size | Sum of all physical backup, snapshot backup, and log backup sizes |
Free quota | Instance storage space × 200% (snapshot backup quota applies during coexistence) |
Unit price | Based on the backup mode after switching: snapshot → physical uses the physical backup unit price; physical → snapshot uses the snapshot backup unit price |
Example 1: Snapshot backup switched to physical backup
Item | Value |
Instance region | China (Hangzhou) |
Instance storage space | 20 GB |
Snapshot backups retained | 40 GB (data backup: 20 GB, log backup: 20 GB) |
Physical backups generated | 20 GB (data backup: 10 GB, log backup: 10 GB) |
Unit price | 0.00004 USD/GB/hour (physical backup, as the current mode) |
Calculation:
Free quota = 20 GB × 200% = 40 GB (snapshot quota applies during coexistence)
Total = 40 GB + 20 GB = 60 GB
Excess = 60 GB − 40 GB = 20 GB
Hourly fee = 20 GB × 0.00004 = 0.0008 USD/hour
Example 2: Physical backup switched to snapshot backup
Item | Value |
Instance region | China (Hangzhou) |
Instance storage space | 20 GB |
Physical backups retained | 20 GB (data backup: 10 GB, log backup: 10 GB) |
Snapshot backups generated | 40 GB (data backup: 20 GB, log backup: 20 GB) |
Unit price | 0.00004 USD/GB/hour (snapshot backup, as the current mode) |
Calculation:
Free quota = 20 GB × 200% = 40 GB (snapshot quota applies during coexistence)
Total = 20 GB + 40 GB = 60 GB
Excess = 60 GB − 40 GB = 20 GB
Hourly fee = 20 GB × 0.00004 = 0.0008 USD/hour
Usage notes
Data and log backups are stored in independent backup storage and do not occupy instance storage space.
Backup fees depend on total backup size, not instance storage space usage. To check fees, look at your total backup size, not storage space usage.
For cloud disk instances in snapshot backup mode, certain control operations that replace cloud disks — such as secondary database rebuilding — can increase backup costs. These operations increase snapshot chains, which cause growth in:
Backup storage fees (billable item code: BackupCharged)
Cross-region backup traffic fees (billable item code: NetworkOutDuplicationSize)
Cross-region backup storage fees (billable item code: DdrOssStorageSize)
DDL operations that cause excessive secondary database latency may trigger automatic secondary database rebuilding. This increases snapshot chains, raising backup storage and network traffic costs.
Reduce backup fees
Reduce backup size
Lower the backup frequency to generate fewer backup sets. See Back up SQL Server data.
Shorten the backup retention period so the system automatically deletes older backups. Manual deletion of backup sets is not supported. See Back up SQL Server data.
Increase the free backup quota
The free quota is proportional to instance storage space. Expanding storage space directly increases your free quota.
For example, with snapshot backup enabled, expanding from 150 GB to 300 GB raises the free quota from 300 GB to 600 GB.
See Change the specifications of an RDS SQL Server instance.
FAQ
The automatic backup of my RDS instance has exceeded the free quota and is now being charged. How can I turn off the backup feature?
Automatic backups are enabled by default and cannot be turned off. To reduce charges, modify the automatic backup policy to delete existing backups or reduce the rate at which new backups are generated.
I shortened the backup retention period from x days to y days, but the backup size hasn't changed. Why?
If no existing backup files are older than y days, no files are deleted and the backup size remains unchanged. The retention period only removes backups that have exceeded the specified duration.
Where can I view my total backup size and free quota?
Go to the instance details page in the console and navigate to Basic Information > Instance Resources > Backup Usage.
Why is my total snapshot backup size larger than my actual data file size?
Snapshot backups are calculated based on cloud disk storage blocks, not actual data file size. Storage blocks are allocated in fixed sizes (such as 4 MB). When data is written in a scattered pattern, a small amount of data can occupy multiple blocks (for example, 3 MB of data may occupy 2, 3, or even more storage blocks). As a result, the total number of non-empty storage blocks — and therefore the snapshot backup size — can exceed the actual data size.