AWS Cost Anomaly Detection - Net Amortized Cost vs Unblended Cost


I am trying to set up AWS Cost Anomaly Detection to help detect anomalous spend patterns in my account. I have EC2 reservations in my account that are upfront costs at the start of the month that show up as large spikes in my monthly spend. I read in the AWS Cost Anomaly Detection documentation that it monitors net unblended cost data from Cost Explorer, however I would like it to instead monitor using net amortized cost data so that my spike from EC2 reservations at the start of each month are not detected as anomalies.

Is there any way to make sure that the AWS Cost Anomaly Detection service uses net amortized cost to monitor rather than the net unblended cost?

asked a month ago208 views
1 Answer
Accepted Answer


AWS Cost Anomaly Detection directly uses the net unblended cost data from Cost Explorer and cannot be configured to use net amortized cost.

  • AWS Cost Anomaly Detection looks for unusual spikes in your spending.
  • It uses your actual bill (net unblended costs) to spot these spikes because this shows exactly when you were charged.

After your billing data is processed, AWS Cost Anomaly Detection runs approximately three times a day in order to monitor for anomalies in your net unblended cost data (that is, net costs after all applicable discounts are calculated). You might experience a slight delay in receiving alerts. Cost Anomaly Detection uses data from Cost Explorer, which has a delay of up to 24 hours. As a result, it can take up to 24 hours to detect an anomaly after a usage occurs. If you create a new monitor, it can take 24 hours to begin detecting new anomalies. For a new service subscription, 10 days of historical service usage data is needed before anomalies can be detected for that service.

There is workaround for the solution to try adjusting the thresholds, i never tried it But these resources may help you

Official Links:

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answered a month ago
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reviewed a month ago
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reviewed a month ago
  • Thanks for your response!

    Do you know of any other AWS services that can be configured to monitor the Net Amortized Cost for an account and then alert on anomalies? Can CloudWatch anomaly detection be configured in this way?

  • One nuance that should not be overlooked is that Cost Anomaly Detection is a machine learning feature that allows you to provide feedback on whether the anomaly was "accurate" (eg. a real anomaly in usage), a "false positive" (eg. an expected pattern of usage), or "not an issue" (eg. anomalous usage, but expected - perhaps due to the launch of a new workload).

    By providing feedback on the anomalies, Cost Anomaly Detection learns what usage is expected. Over time, this is factored into the daily, weekly, and monthly patterns that Cost Anomaly Detection uses when analyzing your usage.

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