Explanation
NAT Gateways are convenient for enabling outbound access from private subnets, but in data-intensive environments, they can quietly become a major cost driver. When large volumes of traffic flow through the gateway-particularly during batch processing, frequent software updates, or hybrid cloud integrations-the per-GB charges accumulate rapidly. In some cases, replacing a managed NAT Gateway with a self-managed NAT instance can substantially reduce costs, provided that the organization is prepared to operate and maintain the alternative solution.
Relevant Billing Model
NAT Gateway pricing includes:
- Hourly cost per deployed gateway per Availability Zone
- Per-GB data processing fees for all traffic routed through the gateway
These charges apply regardless of usage pattern and can scale significantly in high-throughput environments.
Detection
- Identify NAT Gateways with consistently high data processing volumes over the lookback period
- Review per-GB transfer charges to assess whether NAT Gateway usage represents a significant portion of total networking costs
- Determine whether traffic patterns are driven by expected workload behavior or architectural inefficiencies
- Evaluate whether alternative designs-such as VPC endpoints or NAT instances-could reduce data processing costs
- Consider that replacing a managed NAT Gateway with a self-managed NAT instance introduces operational overhead (e.g., scaling, patching, monitoring).
- Confirm whether the potential savings outweigh the additional management effort
Remediation
In environments with large volumes of outbound traffic, consider replacing the managed NAT Gateway with a self-managed NAT instance to reduce per-GB data processing costs. Alternatively, evaluate architectural changes to reduce or avoid NAT usage altogether-such as using VPC endpoints for AWS service access. Weigh the trade-offs between cost savings and the operational complexity of managing your own NAT infrastructure.