Log Analytics Retention Query

Question

Log Analytics Retention Query

Piyush Solanki 0

I am working for optimising log analytics workspace , but I am stuck in calculating the amount of money that can be saved if I change the retention period if it is above the free window provided by azure.
For example I have a log analytics workspace with retention set to 365 days and Azure provide me 90 days for free retention only ingestion cost comes , But Now if I have set the retention to 365 days then I will have to incur cost of 275 days for retention , so i change it again to 90 days then how can i calculate the potential savings that i will have , i want exact money amount.
Also How can i see the amount of the data retained in GB ?

VEMULA SRISAI 13,890 Reputation points Microsoft External Staff Moderator

2026-07-18T17:37:04.13+00:00
Piyush Solanki Yes, you can estimate the potential savings, but Azure does not provide an exact retention savings figure directly. Retention charges are based on the volume of data retained beyond the included retention period.

To estimate the savings:

Billable Retained Data (GB) = Average Daily Ingestion (GB/day) × (Configured Retention Days - Included Retention Days)

For example, if your workspace ingests 10 GB/day and retention is set to 365 days:

10

To view your data volume:

Go to Log** Analytics Workspace > Usage and estimated **costs to review ingestion trends and daily data volume.

You can also run:

Usage | where TimeGenerated > ago(32d) | where StartTime >= startofday(ago(31d)) and EndTime < startofday(now()) | where IsBillable == true | summarize TotalBillableGB = sum(Quantity)/1000. | extend AvgBillableGBPerDay = TotalBillableGB / 31.0

This will show your daily ingestion volume, which can be used to estimate retained data.

Please note that Log Analytics does not expose a single metric showing the exact amount of retained data in GB used for retention billing. The closest estimate is based on ingestion volume and retention settings. Manage data retention: https://learn.microsoft.com/azure/azure-monitor/logs/data-retention-configure

Cost calculations (included days, data size): https://learn.microsoft.com/azure/azure-monitor/logs/cost-logs

Query billable volume (Usage table): https://learn.microsoft.com/azure/azure-monitor/logs/analyze-usage#query-billable-data-volume-from-the-usage-table

Azure Monitor pricing (your exact per-GB rate): https://azure.microsoft.com/pricing/details/monitor/

1 answer

Your answer

VEMULA SRISAI 13,890 Reputation points Microsoft External Staff Moderator

2026-07-18T17:37:04.13+00:00

Piyush Solanki Yes, you can estimate the potential savings, but Azure does not provide an exact retention savings figure directly. Retention charges are based on the volume of data retained beyond the included retention period.

To estimate the savings:

Billable Retained Data (GB) = Average Daily Ingestion (GB/day) × (Configured Retention Days - Included Retention Days)

For example, if your workspace ingests 10 GB/day and retention is set to 365 days:

10

To view your data volume:

Go to Log** Analytics Workspace > Usage and estimated **costs to review ingestion trends and daily data volume.

You can also run:

Usage | where TimeGenerated > ago(32d) | where StartTime >= startofday(ago(31d)) and EndTime < startofday(now()) | where IsBillable == true | summarize TotalBillableGB = sum(Quantity)/1000. | extend AvgBillableGBPerDay = TotalBillableGB / 31.0

This will show your daily ingestion volume, which can be used to estimate retained data.

Please note that Log Analytics does not expose a single metric showing the exact amount of retained data in GB used for retention billing. The closest estimate is based on ingestion volume and retention settings. Manage data retention: https://learn.microsoft.com/azure/azure-monitor/logs/data-retention-configure

Cost calculations (included days, data size): https://learn.microsoft.com/azure/azure-monitor/logs/cost-logs

Query billable volume (Usage table): https://learn.microsoft.com/azure/azure-monitor/logs/analyze-usage#query-billable-data-volume-from-the-usage-table

Azure Monitor pricing (your exact per-GB rate): https://azure.microsoft.com/pricing/details/monitor/

Answer 1

Welcome to Microsoft Q&AHello @Piyush Solanki I hope you are doing well.

The savings cannot be calculated directly from the retention setting alone because Microsoft charges for retained data based on the average volume of data retained beyond the included retention period, not simply by multiplying the current storage by the number of days.

To estimate your potential savings, you should first determine how much data is being retained beyond the included retention period.

1. Check your current retention settings

In your Log Analytics workspace:

Log Analytics Workspace > Usage and estimated costs

Log Analytics Workspace > Properties

These pages show your current retention period and daily ingestion volume.

2. Estimate the retained data

If your workspace ingests approximately X GB/day, then the billable retained data is roughly:

Billable retention (GB) =

Daily ingestion (GB/day) × (Configured retention - Included retention)

For example:

Daily ingestion: 10 GB/day

Retention: 365 days

Included retention: 90 days

Then:

10 × (365 - 90) = 2,750 GB

This is the approximate volume subject to long-term retention charges.

3. Calculate the savings

If you reduce retention from 365 days to 90 days, the retained data beyond the included period becomes 0 GB, so your monthly savings would be approximately:

Billable retained GB × Azure retention price per GB-month

The exact amount depends on your region and pricing tier. You can obtain the current rate using the Azure Pricing Calculator.

View how much data is stored

To understand your ingestion patterns, you can run the following KQL query:

Usage

| summarize TotalGB = sum(Quantity) by bin(TimeGenerated, 1d)

| order by TimeGenerated desc

Or review Usage and estimated costs, which provides daily ingestion trends directly in the Azure portal.

Note: Log Analytics does not expose a single metric showing the exact number of GB currently retained for billing purposes. Retention charges are calculated by Azure based on retained data over time, so the closest estimate is derived from your daily ingestion rate and configured retention period.

References:

Azure Monitor Logs pricing:

https://learn.microsoft.com/azure/azure-monitor/logs/cost-logs

Manage Log Analytics workspace retention:

https://learn.microsoft.com/azure/azure-monitor/logs/data-retention-configure

Azure Pricing Calculator:

https://azure.microsoft.com/pricing/calculator/

If my answer helped you, please consider marking it as accepted. This helps others in the community find similar solutions.

Jose Benjamin Solis Nolasco 10,891 Reputation points Volunteer Moderator

2026-07-18T02:17:13.87+00:00

@Piyush Solanki Just following up, Do you need more guidance or assistance ?

If all your concerns have been resolved, I would greatly appreciate it if you could mark the answer as "Accepted." This helps both us and others in the community.
Jose Benjamin Solis Nolasco 10,891 Reputation points Volunteer Moderator

2026-07-29T13:43:17.4033333+00:00

@Piyush Solanki Just following up, Do you need more guidance or assistance ?

If all your concerns have been resolved, I would greatly appreciate it if you could mark the answer as "Accepted." This helps both us and others in the community.