Azure Blob Size

To get the size of an Azure Blob Storage container and understand quota options, use the following supported approaches.

1. Calculate container size

There is no built-in per-container size metric, but container size can be calculated by summing the sizes of all blobs in that container.

Two documented options:

a. Using Azure Storage inventory + Azure Synapse (recommended for many containers / large accounts)

1. Enable Azure Storage blob inventory on the storage account and ensure the Content-Length field is included in the inventory schema.
2. Once an inventory CSV report is generated, use Azure Synapse serverless SQL to aggregate size per container.
3. Run a query like this against the inventory CSV:

SELECT LEFT([Name], CHARINDEX('/', [Name]) - 1) AS Container,
       COUNT(*) As TotalBlobCount,
       SUM([Content-Length]) As TotalBlobSize
FROM OPENROWSET(
    bulk '<URL to your inventory CSV file>',
    format='csv', parser_version='2.0', header_row=true
) AS Source
GROUP BY LEFT([Name], CHARINDEX('/', [Name]) - 1)

TotalBlobSize gives the total size of all blobs in each container.

b. Using Azure CLI to total blob sizes in a single container

There is a script pattern that:

• Uses az storage blob list to list all blobs in a container.
• Sums their sizes to produce an estimated container size.

Notes from the script:

• It “calculates the size of a container in Azure Blob storage by totaling the size of the blobs in the container.”
• It is an estimate and “should not be used for billing calculations.”
• A single listing call returns up to 5000 blobs; continuation tokens are required for more.

2. Quotas / limits for a blob container

Per-container hard quotas cannot be configured. Relevant limits:

• “Maximum size of single blob container | Same as maximum storage account capacity.”
• Other limits (max blob size, max blocks, etc.) apply per blob, not as a configurable quota per container.

So:

• A container can grow up to the storage account’s capacity target; there is no native feature to set a smaller, enforceable quota on an individual container.
• To “limit” usage per container, use monitoring and alerting:
  • Use Storage inventory plus aggregation (as above) to monitor capacity per container.
  • Use Azure Monitor / Log Analytics queries to track usage and operations per container and trigger alerts when thresholds are exceeded.

Example monitoring pattern:

• Use blob inventory to “take an inventory of blobs with size information” and “aggregate the size and count at the container level.”
• This is explicitly recommended for scenarios where data is partitioned by container and capacity per container (for example, per customer) must be monitored.

References:

• Calculate blob count and total size per container using Azure Storage inventory
• Calculate the size of a Blob storage container
• Best practices for monitoring Azure Blob Storage
• Scalability and performance targets for Blob storage
• Azure subscription and service limits, quotas, and constraints