Estimated monthly savings
Cost Optimization Hub analyzes specific pricing discounts to provide you with a measure of your cost efficiency. This is done by dividing the aggregated estimated monthly savings of your cost optimization opportunities by your amortized monthly Amazon costs, exclusive of credits and refunds.
For recommendations associated with a resource, estimated monthly cost impact is an estimation of how much your Amazon bill will change over a 730-hour period (365 * 24 /12). This estimate excludes the periods when the resources were not running and if you had implemented the recommended action 730 hours ago. If the recommendation has a different lookback period, the cost impact is normalized to a 730-hour period, which is the average number of hours per month.
Note that your estimated monthly savings is a quick approximation of future savings. The actual savings that you realize is dependent on your future Amazon usage patterns.