A Practical Way to Estimate Costs When Moving from GPv1 to GPv2 Storage Accounts

Microsoft is retiring GPv1 storage accounts, which means every organisation still using them must migrate to GPv2. The migration itself is simple—but the real question most teams face is: what will this change do to our costs? This guide breaks down a practical, data-driven method to predict your Hot vs. Cool tier costs based on your own usage metrics.

Why Microsoft Is Retiring GPv1 Storage Accounts

GPv1 storage accounts were introduced many years ago, and over time Microsoft has shifted investment toward GPv2, which offers:

• Modern pricing models
• Access tiers (Hot and Cool)
• Improved performance consistency
• Better integration with new Azure features

Because GPv2 is now the standard, Microsoft is deprecating GPv1 accounts.
This means everyone must migrate—whether you want to or not.

The upgrade is straightforward, but your cost model will change.
And that’s why cost estimation matters.

Microsoft’s official migration guidance:
https://learn.microsoft.com/en-us/azure/storage/common/general-purpose-version-1-account-migration-overview

Why Cost Estimation Matters

Even though the GPv1 → GPv2 upgrade is no-downtime and done from the Azure Portal, the cost model shifts to tier-based pricing:

• Hot tier → higher per-GB price, no retrieval fees
• Cool tier → lower per-GB price, but read/retrieval fees

Most teams ask:

“Which tier is cheaper for our workload?”

Unfortunately, the Azure Pricing Calculator can only provide estimates because it doesn’t know:

• how often you read data
• how many writes occur
• which APIs your applications call
• how metadata-heavy your workload is
• your real 30-day usage pattern

That’s why a calculator based on your actual telemetry gives the most reliable answer.

About the GPv1 → GPv2 Cost Calculator

We created a simple Excel-based calculator that:

• Takes your 30-day API-level metrics
• Maps those to Azure billing categories
• Compares Hot vs. Cool tier costs
• Factors in your average storage size
• Shows exactly which tier is cheaper for your workload

This calculator is available separately on our site as a downloadable cheat sheet.

Quick Summary: How the GPv1 → GPv2 Migration Works

The migration process is extremely safe and predictable:

• Done directly through the Azure Portal
• Zero downtime
• No data movement
• Your settings stay intact
• You instantly gain access to Hot and Cool tiers

Microsoft handles the migration internally—you simply trigger it.

The challenge isn’t the upgrade itself.
The challenge is choosing the right tier.

Step 1: Pull Your Storage Account’s API-Level Metrics

In the Azure Portal:

1. Go to your storage account
2. Open Metrics
3. Select Transactions
4. Group by API Name

You’ll see real usage for operations like:

• GetBlob
• PutBlob
• PutBlock
• AppendBlock
• GetBlobProperties
• ListBlobs

These metrics show exactly how your workload behaves.

Step 2: Map Each API to Its Billing Category

Azure groups API operations into cost categories. Example:

The calculator includes these mappings automatically.

Step 3: Add Your Storage Size

Your 30-day average storage size has a major impact on your costs:

• Hot Tier — higher per-GB cost, no retrieval fees
• Cool Tier — lower per-GB cost, retrieval fees apply

Large datasets that are rarely accessed often benefit from the Cool tier.

Active datasets typically fit better in the Hot tier.

Step 4: Let the Calculator Compare Hot vs. Cool Tier

Once you enter:

• your storage size
• your 30-day transaction counts

The calculator quickly shows:

• Your current GPv1 cost
• Your GPv2 Hot tier cost
• Your GPv2 Cool tier cost
• The monthly difference

This gives you a clear, evidence-based answer.

When the Hot Tier Makes Sense

Choose Hot if:

• You have frequent reads
• Your workload is accessed continuously
• You want to avoid Cool-tier retrieval fees
• Your data is actively used (logs, telemetry, app data)

When the Cool Tier Makes Sense

Choose Cool if:

• You store large volumes of data
• Reads are infrequent
• You retain data for compliance or archival
• Your workload is mostly write-heavy

Many GPv1 accounts fall into this category, which is why some organisations see cost savings after moving to GPv2.

Why This Approach Is More Accurate Than the Azure Calculator

The Azure Pricing Calculator cannot see:

• your API behaviour
• your metadata operations
• access frequency
• real read/write distribution
• idle vs active periods

Your actual 30-day metrics tell the truth.

By feeding those metrics into the calculator, you get a clear, defendable recommendation for Hot vs. Cool—based entirely on real data.

Final Thoughts

Microsoft’s retirement of GPv1 accounts means migration is unavoidable.
But choosing the correct tier does not have to involve guesswork.

By using your own metrics and the Hot vs Cool comparison method, you can:

• predict your GPv2 costs accurately
• avoid unexpected charges
• make a well-informed tier decision
• justify your recommendation internally

If you'd like help with:

• GPv1 → GPv2 migration
• Storage tier recommendations
• Azure cost optimisation
• Automated calculators or dashboards

Feel free to reach out. We’re here to support your Azure journey.