Need exact cost estimation for LWA with 100 Debian VMs (500 GB monthly logs)

Azure Monitor / Log Analytics charges for data ingestion (pay-as-you-go per-GB) and for data retained beyond the free retention window. The first 5 GB/month per billing account in the Analytics Logs pay-as-you-go tier is free. Analytics Logs include 31 days (1 month) of retention at no extra retention charge. Data kept beyond that is charged per-GB per month (pro-rated daily). Typical published Pay-As-You-Go ingestion numbers commonly used for East US are $2.30 per GB (ingestion) and $0.10 per GB-month (retention beyond free window). These region-dependent rates are fully documented - so you might want to refer to that documenantion for more details. Btw. you might consider using the Azure Pricing Calculator to verify the info below...

Your numbers & exact monthly cost (analytics / LWA only)

Inputs

• VMs: 100
• Per-VM logs/month: 5.0 GB
• Total ingestion/month: 100 × 5 GB = 500.0 GB

Assumed Pay-As-You-Go unit prices (East US example)

• Ingestion: $2.30 per GB. ([Azure to the Max][2])
• Retention beyond included period: $0.10 per GB-month (charged only for data kept >31 days). ([Thomas Stringer][3])
• Free allowance: first 5 GB/month per billing account are free. ([Microsoft Azure][1])

1. Ingestion cost

• Billable ingestion after free 5 GB: 500 GB - 5 GB = 495 GB
• Ingestion cost = 495 GB × $2.30/GB = $1,138.50

If you (for simplicity) ignore the 5-GB free allowance, ingestion = 500 × $2.30 = $1,150.00. So ingestion cost ≈ $1,138.50 (with 5-GB free) — $1,150.00 (if you ignore the tiny 5-GB credit). ([Microsoft Azure][1])

2. Retention cost (LWA)

• You stated you will export all logs after one month. Analytics Logs include ~31 days retention at no charge, so if you export/clear them within that one-month window, you will not incur any Log Analytics retention charges.
• Retention cost = $0.00 for the scenario “ingest current month, export after 1 month” (assuming you do not keep any data in LWA beyond the included 31 days).

Final answer (exact monthly LWA ingestion + retention)

• Ingestion (pay-as-you-go, East US example): $1,138.50 / month (uses the 5 GB free credit).
• Retention (kept ≤31 days, exported after one month): $0.00 / month.
• Total LWA cost (ingestion + retention): ≈ $1,138.50 / month.

(If you ignore the 5-GB free allowance, total ≈ $1,150.00 / month.)

A few additional considerations:

1. Region and plan matter. The $2.30 and $0.10 numbers are region-dependent examples (East US). If your subscription is in another region the per-GB price may differ. Also, commitment tiers (reserved capacity) can substantially reduce the per-GB ingestion price if you run this volume long-term. See Azure Monitor pricing and the Pricing Calculator for exact regional/commitment tier pricing.
2. Export cost and storage cost are not included. You asked to consider only ingestion and retention in LWA, so I excluded (a) the cost to export data from LWA (Log Analytics Data Export can have its own per-GB export charge) and (b) the cost to store exported logs in Blob Storage — those are separate and would add to your total bill. The Azure docs note export is billed per GB.
3. If you ever keep data past 31 days, retention will start to appear: e.g. storing 500 GB for one extra month beyond the included 31 days would cost roughly 500 × $0.10 = $50 that month (again region-dependent).

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hth

Marcin

Hi Ravi Bhagat,

Thanks for posting your question in the Microsoft Q&A forum.

Since you export the logs after 30 days, you stay within the free retention period, so Azure only charges you for the data being ingested into the workspace.

At the current rate of about $2.30 per GB, 500 GB of logs costs roughly $1,150 per month. If you enable a commitment tier, the price per GB drops and the total can go down to around $800 per month.

No extra retention cost applies because you don’t keep the logs longer than 30 days.

Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful