How Compute Savings Plans Work (Step-by-Step)

Most people understand that a Compute Savings Plan saves money on cloud compute. Far fewer understand the precise mechanism which matters, because getting the commitment amount wrong in either direction costs real money. Too high: you pay for committed hours you do not use. Too low: you miss savings on usage that could have been covered. The difference between a well-sized Savings Plan and a poorly-sized one can easily be tens of thousands of dollars per year on a mid-size fleet. This guide walks through the exact mechanics, hour by hour, with worked examples on both AWS and Azure. Step 1: You Choose a Commitment Amount Before anything else, you decide how much per hour you want to commit. This is the single most important decision in the entire process. Everything else is automatic, the discount application, the coverage calculation, the billing. The commitment amount is a dollar figure: $X per hour. It represents a minimum spend level. You are telling the cloud provider: every hour for the next 1 year (or 3 years), I guarantee I will use at least this much compute. The right commitment amount is your stable baseline, not your average and not your peak. Pull your last 30 days of hourly compute spend. Sort the values. Find the P70 or P75: the spend level you are at or above for 70–75% of hours. That is roughly where your commitment should sit. Why P70–P75 and not the average? Because the average includes your peak hours and your quietest hours equally. If you commit to the average, you generate wasted commitment in the bottom 50% of hours. At P70, you are paying for unused commitment in only 30% of hours and those hours only waste the difference between actual usage and committed amount, not the full committed amount. If you want to understand how commitment-based discounts work across AWS, Azure, and GCP, we covered the full landscape here What Are Commitment-Based Discounts in Multi-Cloud Services? Step 2: The Cloud Provider Applies Discounted Rates Once you have