NAT Gateway cost optimization (high-leverage fixes)

NAT Gateway optimization is unusually measurable: almost everything comes down to gateway-hours and GB processed. The best savings usually come from keeping AWS-service traffic private and eliminating recurring downloads and retry storms that silently multiply outbound traffic.

Step 0: baseline the two drivers

• Gateway-hours: how many NAT gateways are always on (by environment and region)
• GB processed: average and peak (incident) weeks
• Top traffic sources: images, updates, external APIs, log shipping

If you don’t know GB processed yet: estimate GB processed.

1) Keep traffic private (the biggest lever for many teams)

• Use VPC endpoints/private connectivity for common AWS services where available.
• Avoid routing AWS API calls through NAT by accident (it looks like “internet egress” in the NAT bill).
• Validate that route tables and DNS resolution actually keep the traffic on the private path.

Cost comparison: NAT vs VPC endpoints

2) Reduce large recurring downloads (often the hidden baseline)

• Cache OS/package updates where practical (or use internal mirrors).
• Reduce container image size and avoid re-pulling unchanged layers.
• Prevent “download storms” during autoscaling by pre-pulling or staggering updates.

3) Fix retry storms and noisy egress

• Set sane timeouts and jittered backoff for outbound calls.
• Identify the top external destinations (APIs/SaaS) and validate volume against business expectations.
• Watch “polling” and keepalive patterns that create constant egress even at low traffic.

4) Reduce non-prod waste

• Schedule dev/test workloads so NAT isn’t needed 730 hours/month.
• Don’t mirror production traffic volumes into staging unless required.
• Use smaller test datasets to reduce background job egress.

5) Endpoint-first checklist (common NAT drivers)

A fast way to reduce NAT processed GB is to identify which traffic is going to AWS services and keep it on a private path. Common NAT drivers to check (availability varies by region/service):

• Object storage access (often large and steady)
• Container registry pulls (large bursts during deploys/autoscaling)
• Security token / identity calls (small per call, but can be high frequency)
• Monitoring/logging APIs (can be noisy in large fleets)

Practical flow: identify top NAT destinations, pick the top 1–2 AWS-service buckets, then validate the NAT GB drop after enabling private connectivity.

6) Validate savings (and ensure costs didn’t just move)

• Confirm GB processed dropped and identify which source changed.
• Check cross-AZ transfer and internet egress costs after routing changes.
• Re-check incident windows; if retries still spike, monthly savings will erode.

Tools and next steps

Sources

• Amazon VPC pricing (NAT Gateway)
• AWS PrivateLink overview (for private connectivity context)

Related guides

Related calculators

FAQ