Introduction.
When it comes to building and deploying applications on the cloud, ensuring your services are both highly available and scalable is crucial. This is where load balancers play a vital role, helping distribute incoming network or application traffic across multiple servers to improve performance, reliability, and fault tolerance.
Among the various load balancing solutions offered by Amazon Web Services (AWS), the Application Load Balancer (ALB) stands out as a powerful and flexible choice designed to handle HTTP and HTTPS traffic with advanced routing capabilities. It allows developers to direct traffic based on URL paths, hostnames, or request headers, making it ideal for modern microservices architectures and containerized applications.
However, while AWS ALB offers many features, understanding its pricing model is essential for anyone looking to manage cloud costs effectively. AWS pricing can often seem complex to beginners because charges are based on multiple factors, not just on the number of hours the service is running. Specifically, ALB pricing involves a combination of fixed hourly fees and variable charges based on a unique metric called Load Balancer Capacity Units (LCUs).
LCUs represent different dimensions of your load balancer’s usage, such as the number of new connections, active connections, processed data volume, and the number of rule evaluations your load balancer performs. Because of these layers, predicting your ALB costs without a clear understanding can lead to surprises in your cloud bill. For startups and enterprises alike, managing costs is as critical as managing performance, and having a solid grasp of how ALB pricing works allows you to design your infrastructure to be both efficient and cost-effective.
This guide aims to simplify the AWS ALB pricing model by breaking down its components in clear, straightforward language tailored for beginners. We will explore what Load Balancer Capacity Units are, how they influence your monthly costs, and why certain traffic patterns or configurations might increase your spending.
Additionally, we’ll provide practical tips and strategies to estimate your ALB costs accurately and optimize them without sacrificing the performance your users expect. By the end of this guide, you’ll not only understand the AWS ALB pricing model but also be equipped to make informed decisions about deploying, scaling, and monitoring your load balancers within AWS.
Whether you’re running a small web application, a microservices environment, or a complex distributed system, mastering ALB pricing is a key step toward effective cloud cost management. So, let’s dive in and demystify AWS ALB pricing together!
What Is AWS Application Load Balancer (ALB)?
AWS ALB is a Layer 7 load balancer that routes incoming HTTP/HTTPS traffic to targets like EC2 instances, containers, and IP addresses. It supports advanced routing features such as path-based routing, host-based routing, and WebSockets.
Because it handles traffic intelligently and scales automatically, ALB is a popular choice for modern, scalable applications.
AWS ALB Pricing Components
AWS charges for ALB usage based on two main components:
1. Load Balancer Hours
You pay a fixed hourly rate for each Application Load Balancer you run, regardless of traffic. This fee applies as long as your ALB is active, even if it’s handling zero requests.
2. Load Balancer Capacity Units (LCUs)
LCUs are a unique metric AWS uses to measure how much traffic and workload your ALB processes. Your hourly usage is billed based on the highest number of LCUs consumed in any hour.
What Are Load Balancer Capacity Units (LCUs)?
LCUs represent four dimensions of ALB traffic. AWS calculates your usage based on whichever dimension consumes the most units in a given hour:
- New Connections per second: Number of new TCP connections
- Active Connections: Number of concurrent TCP connections
- Processed Bytes: Data volume processed (ingress + egress)
- Rule Evaluations: Number of rules evaluated per request
Example: If you have 500 new connections per second but only 100 active connections and moderate data, the new connections dimension will determine your LCU usage.
How Much Does AWS ALB Cost?
Pricing varies by region, but here’s a typical example (prices are approximate):
| Pricing Component | Cost (US East – N. Virginia) |
|---|---|
| Load Balancer Hour | $0.0225 per hour |
| LCU | $0.008 per LCU per hour |
So, if your ALB runs 24/7 and averages 3 LCUs per hour, your monthly cost estimate would be:
- Load Balancer Hours: 24 hours x 30 days x $0.0225 = $16.20
- LCUs: 24 hours x 30 days x 3 LCUs x $0.008 = $17.28
- Total: ~$33.48 per month
Estimating Your ALB Costs
To estimate your costs, consider the following:
- How many ALBs will you run? Each ALB has a base hourly fee.
- What’s your expected traffic pattern? Look at connections, data throughput, and rules evaluated.
- Use AWS Pricing Calculator: AWS offers an online tool where you can input your expected traffic to get cost estimates.
Tips to Optimize AWS ALB Costs
- Consolidate ALBs: Use fewer load balancers by combining services behind one ALB with path or host-based routing.
- Reduce unnecessary rules: Complex routing rules increase rule evaluations, driving up LCUs. Keep rules efficient.
- Monitor and analyze traffic: Use AWS CloudWatch to track LCU usage and spot cost spikes early.
- Right-size your architecture: Avoid over-provisioning targets and balance traffic efficiently.
- Consider alternative load balancers: For simple TCP/UDP traffic, Network Load Balancer (NLB) might be more cost-effective.
Conclusion
Understanding AWS ALB pricing is essential for controlling your cloud costs while maintaining reliable, scalable application delivery. Remember that your monthly bill depends not just on how many load balancers you run, but also on the traffic, connection patterns, and rule complexity.
Use the AWS Pricing Calculator and monitoring tools to keep your ALB costs predictable and optimize continuously as your application grows.