Why are two small SQL databases being charged at 25 times more than others of the same type on the same Azure SQL server??

Hello John T

Thank you for posting your query on Microsoft Q&A platform.

Even if two databases are tiny (100–120 MB), Azure SQL charges are not based on DB size. Charges depend almost entirely on Compute Tier + Compute Size, not storage.

When two databases suddenly cost ~£9.36/day while others cost ~£0.37/day, the cause will always fall under one of these platform‑level billing mechanisms:

1. They were created in a different (more expensive) Pricing Tier: The reason for the huge cost difference is that your older databases are running on a low‑cost tier such as Basic or S0 (typically £0.30–£0.50 per day), while the two new databases were created on a much higher compute tier such as S2, S3, Premium, Business Critical, or vCore‑based (commonly £8–£12+ per day). Even small 100–120 MB databases become expensive immediately if they are placed on these higher tiers, and the Azure portal can sometimes default to these tiers when creating new databases.
2. They were created as Hyperscale or vCore-based DBs: vCore tiers (especially Business Critical) cost significantly more. Portal sometimes defaults to vCore if the user previously viewed a vCore SKU. Symptoms match exactly: £9.36/day ≈ 1–2 vCores General Purpose.
3. The new databases are in an Elastic Pool with a high eDTU / vCore allocation: If you placed the two DBs inside an elastic pool with high compute units. You pay for the pool, not per DB.Cost analysis allocates pool cost proportionally to active databases.

If only 2 DBs are in that pool → their per‑DB “shown” cost spikes.

This scenario produces misleading per‑database cost values but accurate overall billing.

4. Long-term retention (LTR) or backups on Premium storage: If LTR was enabled automatically (e.g., via policy), backup storage costs can spike. But this usually does not reach £9/day unless retention is long and region is expensive. This is a less likely but still possible cause.
5. The databases are using features that trigger Premium storage:

Examples:

Geo-redundant backups

Zone redundancy

Accelerated database recovery (ADR) overhead

While these add cost, they do not explain a 25× spike alone. They typically add marginal costs.

The only Azure SQL billing change that matches your exact scenario is:

The two databases were created in a higher compute tier (DTU or vCore), different from the existing 4 databases.

To verify immediately for each of the two costly databases:

Go to Azure Portal → SQL Database → (DB Name)

Open Compute + storage

Check these fields:

Service Tier (Basic / Standard S0 / S1 / S2 / Premium / GP / BC / Hyperscale)

Compute Size (DTU or number of vCores)

Elastic Pool membership

Compare these with the older 4 databases.

You will almost certainly find they are not on the same tier.

Support Request:

You can open support requests in the Azure portal from a service's Azure portal menu, global header, or resource menu. Before you can submit a support request, you must have the appropriate permissions.

You must have appropriate access to a subscription before you can create a support request for it. This means that you must have the role of Support Request Owner, Contributor, or Supporter Contributor, or a custom role with Microsoft.Support/*, at the subscription level.

You can contact Azure support directly using the links below:

https://portal.azure.com/#view/Microsoft_Azure_Support/HelpAndSupportBlade/~/overview

Follow the instructions to provide details about the issue. From the Resources menu, go to the Help section and select "Support + Troubleshooting". In the "Support + Troubleshooting" window on the right, type "Billing" in the search box, select Billing, and click "Next." Select your subscription and click "Next." You'll see some suggestions for resolving the issue. If not, follow the steps below.

Scroll down and you'll find the 'Contact Support' option. From there, select 'Create Support Request'.

Enter a description of the issue (Issue Type, Subscription, Summary, Issue Type - Billing Support, Issue Detail Type)

When the solution reappears, click 'Return to Support Request'. Click Next to create a billing support ticket.

Please let us know if the solutions suggested above helped you or if you need further assistance with this issue.

Thanks,

Suchitra.