Introduction
NAT Gateway is the AWS service most teams overpay for, and they usually don't notice until the bill is already in four figures. Every time I run an AWS NAT Gateway cost optimization review for clients, the same mistakes show up on the bill.
NAT Gateway charges are one of the most common hidden costs in AWS, not because the pricing is literally hidden. It's right on the VPC pricing page: $0.045 per hour idle, $0.045 per GB processed, $0.09 per GB for internet egress on top. What stays hidden is how much traffic is actually flowing through the gateway. Most teams never go back to check after the initial setup. A few terabytes of accidental S3 or ECR traffic move through the gateway every month, and the bill keeps growing before anyone notices.
After five years of building VPCs on AWS for in-house and client-led projects, these are the five AWS NAT Gateway mistakes I keep seeing. Each one has a fix that takes less than a day and saves a big amount on your AWS bills.
Mistake 1: Routing S3 and DynamoDB traffic through NAT Gateway
