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How It Works
A load balancer sits in front of your application and routes each incoming request to one of several backend instances based on a set of rules. Those rules can be as simple as round-robin (each instance takes a turn) or more sophisticated, such as routing based on current CPU utilization or geographic proximity to the user. On AWS, this service is called Elastic Load Balancing (ELB), which includes Application Load Balancers, Network Load Balancers, and Gateway Load Balancers. Azure offers Azure Load Balancer and Azure Application Gateway. GCP provides Cloud Load Balancing. All three operate on a similar principle: keep traffic flowing evenly so no single instance fails under pressure.
Why It Matters for Cloud Cost
Load balancers are not free. Each load balancer incurs an hourly charge plus a usage-based fee tied to the volume of data processed. If your architecture over-provisions load balancers, runs them in idle states, or routes traffic inefficiently, the cost adds up quickly. On the other side, under-provisioning can cause instance failures, application downtime, and emergency scaling events that cost significantly more than a well-tuned setup. Teams that right-size their instances and pair them with a properly configured load balancer typically see more predictable compute bills because autoscaling can respond to real demand rather than brute-force over-capacity.
Usage AI’s ClearCost provides showback reporting and visibility into cloud spend, helping teams identify and act on waste across their infrastructure.