The EC2 NAT Gateway Charge: Why Your Bill is High

You open Cost Explorer. You see a huge spike in EC2-Other. You drill down, and there it is: NatGateway-Bytes.

Why is this charge so high? And why is it buried under “EC2”?

What is “EC2-Other”?

AWS groups many networking and ancillary service costs under the “EC2” service umbrella. This includes:

• EBS Volumes (sometimes)
• Elastic IP addresses
• NAT Gateways
• Data Transfer

This makes it confusing because you think, “I only have 2 small instances running!”

The “Double Dip” Charge

The most confusing part of the NAT Gateway charge for EC2 users is the double billing on data.

Imagine your EC2 instance sends a file to the internet.

1. EC2 Data Transfer Out: You pay standard egress rates (start at $0.09/GB) for the traffic leaving AWS.
2. NAT Gateway Processing: You also pay $0.045/GB for that traffic to pass through the specific gateway device.

So for every GB of internet traffic from a private subnet, you are paying $0.135/GB (0.09 + 0.045), effectively paying a 50% “privacy tax.”

Finding the Leak

To find which specific instance is driving up the NAT cost:

1. Enable VPC Flow Logs.
2. Query logs with CloudWatch Insights.
3. Filter for traffic where dstAddr is outside your VPC CIDR and srcAddr is your private instances.

You will often find a single “chatty” agent (like a logging sidecar or a backup script) that is uploading terabytes of data unnecessarily.

[!TIP] Need to visualize this cost? We broke down the specific math in our NAT Gateway Pricing Calculator. Use it to see how much you could save by reducing processing volume.