Why do I get billed for 4000+hours of alb usage for just two albs?

Hi,

Did you include the cost of LCUs (=Load Balancer Capacity Units) in your computations:

See https://aws.amazon.com/elasticloadbalancing/pricing/

LCU Details
An LCU measures the dimensions on which the Application Load Balancer processes your 
traffic (averaged over an hour). The four dimensions measured are:
1. New connections: Number of newly established connections per second. Typically, 
many requests are sent per connection. 
2. Active connections: Number of active connections per minute.
3. Processed bytes: The number of bytes processed by the load balancer in GBs 
for HTTP(S) requests and responses.
4. Rule evaluations: The product of the number of rules processed by your load 
balancer and the request rate. The first 10 processed rules are free 
(Rule evaluations = Request rate * (Number of rules processed - 10 free rules).

You are charged only on the dimension with the highest usage. An LCU contains:

* 25 new connections per second.
* 3,000 active connections per minute or 1,500 active connections per minute 
while using Mutual TLS.
* 1 GB per hour for Amazon Elastic Compute Cloud (EC2) instances, containers, and
 IP addresses as targets, and 0.4 GB per hour for Lambda functions as targets. When 
using the Mutual TLS feature, data processed includes the bytes for the certificate 
metadata that the load balancer inserts into headers for every request that is routed to the targets.
* 1,000 rule evaluations per second

Best,

Didier

In my view, you should have been charged for the ~1488 hours that you were expecting. Perhaps you could check what Cost Explorer shows if you filter out the Charge type of Tax, only include the load balancer hour Usage type, and select Daily for Granularity. If the load balancers have any tags that you've enabled for billing, such as the Name tag, select that tag (or one of them) for the Group by field.

That should quickly show if there's been some unexpected peak during the month, or if you're getting charged more than expected continuously and at a constant rate, or if the usage for last month has been what you expected but you were charged for past use for some reason instead, or if the extra charge is for something other than the ALB itself, such as its public IPv4 addresses. The cost allocation tag, if available, might also help to isolate if the same difference applies equally to both load balancers, or if there might be another, perhaps untagged resource somewhere in addition to the two ALBs.