Topic
Commitments
Commitments are the largest single discount AWS offers, and the easiest one to get wrong in both directions.
Reserved Instances and Savings Plans can take 30 to 60 percent off compute spend in exchange for a one- or three-year commitment. AWS's own recommendation tooling is a solid starting point. The hard part is what it cannot see: your roadmap, your migration plans, and the difference between a usage floor and a usage average.
Under-commit and you pay on-demand rates for steady-state load, which is money left on the table every hour. Over-commit and you own capacity that outlived its workload. Both failure modes come from the same root: sizing commitments to a forecast instead of a measured, hourly usage floor.
This page holds our deepest research area: how each commitment type actually applies, how discounts flow in consolidated billing, and how to size coverage you will not regret in month eighteen.
Glossary
What Is a Reserved Instance? AWS Reservations, Explained
A Reserved Instance is a billing discount, not a physical server: commit to an instance family for one or three years and pay up to 72 percent less.
What Is a Savings Plan? AWS Commitment Pricing, Explained
A Savings Plan is an AWS pricing agreement: commit to a fixed hourly compute spend for one or three years and pay up to 72 percent less than on-demand.
Related topics
Compute
EC2, Lambda, and Fargate. Instance families, rightsizing, and the price of idle capacity.
Databases
RDS, Aurora, DynamoDB, ElastiCache, and Redshift. Engine choice and provisioning against real load.
Billing fundamentals
How the AWS bill is built. The CUR, rate types, cost allocation tags, and reading an invoice.