Regional NAT Gateway Cost vs. Zonal: Which is Cheaper?

There is a common misconception that AWS offers a “Regional” NAT Gateway—a single gateway that handles traffic for all Availability Zones (AZs) without cross-AZ charges.

This does not exist.

AWS NAT Gateways are Zonal resources. They live in a specific subnet in a specific AZ. This distinction is critical for your bill.

The “One Gateway” Trap

You can route traffic from all your subnets (in AZ A, B, and C) to a single NAT Gateway in AZ A. This usually happens when people try to save money by running only one gateway ($32/mo) instead of three ($98/mo).

But this introduces the Cross-AZ Data Transfer Tax.

Scenario: The Hidden Cost

1. Server in AZ B wants to download a file.
2. Traffic goes from AZ B -> AZ A (to reach the NAT Gateway).
3. Traffic goes from NAT Gateway -> Internet.

You pay twice:

1. Cross-AZ Data Transfer: $0.01/GB (in) + $0.01/GB (out) between AZs.
2. NAT Gateway Processing: $0.045/GB.

If you have heavy traffic, the extra $0.02/GB cross-AZ fee can quickly cost more than the ~$65/mo you saved by skipping the extra gateways.

When to use Zonal vs “Regional” Architecture

1. Zonal Architecture (Recommended)

One NAT Gateway in every AZ where you have workloads.

• Pros: Highest reliability, no cross-AZ data charges.
• Cons: Higher fixed cost ($32/mo per AZ).
• Best for: Production clusters, high-traffic apps.

2. Centralized Architecture (The “Budget” approach)

One NAT Gateway total, shared by all AZs.

• Pros: Only one fixed monthly fee ($32/mo).
• Cons: If AZ A goes down, the entire region loses internet access. You pay cross-AZ fees.
• Best for: Dev/Staging environments where downtime is acceptable and traffic is low.

[!WARNING] Don’t guess. Calculate the break-even point using our NAT Gateway Pricing Calculator. It will tell you if the cross-AZ fees are higher than the fixed gateway savings.