AWS NAT Gateway Is Draining Your Budget — Here Are the Cheaper Alternatives

AWS billing keeps getting worse, not better with all the hidden service charges flying around — but NAT Gateway is the one that really stings. Every startup founder I know has had the same moment: you open your first real AWS bill, squint at the EC2 section, and think what is all this? I’ve been there. Running a small SaaS product, maybe 200GB of outbound traffic a month, genuinely baffled by why the bill kept climbing. Two hours of Cost Explorer drilling later, I found it. NAT Gateway. Three of them — one per availability zone — quietly billing me every single hour whether I used them or not. Equal parts embarrassing and expensive. Apparently that’s a rite of passage.

So here’s a practical breakdown of what NAT Gateway actually costs, plus four concrete alternatives that can cut that line item dramatically. Real numbers. Not ballpark estimates. If you’re running Lambda functions, ECS tasks, or EC2 instances that need to reach AWS services from a private subnet, you’re almost certainly overpaying right now.

Why NAT Gateway Costs Surprise Everyone

The pricing structure is why nobody sees it coming. NAT Gateway hits you on two dimensions simultaneously: an hourly rate per gateway, and a per-gigabyte data processing fee on top of that. Neither one is enormous on its own. Together, they add up fast.

Current rates in us-east-1 — $0.045 per NAT Gateway hour and $0.045 per GB processed. Run the math for a month. One NAT Gateway costs about $32.40 in hourly charges alone ($0.045 × 720 hours). Add data processing and you’re at roughly $37.96 per month per gateway before you’ve pushed a single meaningful byte of application traffic through it.

Here’s where startups get caught. The AWS Well-Architected Framework recommends deploying across multiple availability zones for resilience — genuinely good advice. But most teams implement the standard pattern without thinking hard about the cost multiplier: private subnets in three AZs, one NAT Gateway per AZ. Three gateways means three times the hourly fee. At 500GB of data processed per month across all three, the numbers look like this:

• Hourly charges — 3 × $32.40 = $97.20/month
• Data processing — 500GB × $0.045 = $22.50/month
• Total — roughly $119.70/month

Round up for minor variance and you’re past $140 easily. Not catastrophic for a funded startup — but here’s what actually stings. A huge percentage of that data processing fee is often traffic going to S3 or DynamoDB. Services that don’t need to go through NAT Gateway at all.

The dev environment problem makes everything worse. Many teams mirror their production architecture in staging and dev. Suddenly you’re running six or nine NAT Gateways across environments. I’ve seen teams spending $400/month on NAT across three environments, the dev gateways essentially idle — processing maybe 20GB a month — but the hourly meter never stops. The other trap is that NAT Gateway doesn’t appear as one screaming line item. It shows up buried under EC2 service charges, often split across data transfer categories. Easy to miss until you build a cost allocation tag strategy or filter Cost Explorer by usage type.

Gateway VPC Endpoints — Free for S3 and DynamoDB

I’m burying the lede a bit — sorry. Gateway VPC Endpoints are completely free. No hourly charge, no data processing fee, nothing. And for most startups, traffic to S3 and DynamoDB represents the largest single chunk of what’s flowing through NAT Gateway anyway.

But what is a Gateway VPC Endpoint? In essence, it’s a route table entry that sends traffic directly to S3 or DynamoDB through AWS’s internal network instead of out through NAT and over the public internet. But it’s much more than that — the traffic never leaves the AWS backbone at all. Faster, free, and arguably more secure. That’s what makes Gateway Endpoints endearing to us cost-conscious builders.

Setting Up a Gateway VPC Endpoint for S3

In the AWS Console — VPC → Endpoints → Create Endpoint. Select “AWS services” as the service category. Search for “s3” and select the Gateway type, not Interface. The Gateway type is the free one. Select your VPC. Then, critically, select every route table associated with your private subnets. Hit create. AWS automatically adds a route entry with a prefix list destination to each selected route table. Any traffic destined for S3 public IP ranges now bypasses NAT Gateway entirely.

Setting Up a Gateway Endpoint for DynamoDB

Identical process. Search for “dynamodb” in the endpoint service list, select Gateway type, attach to your private subnet route tables. Done in under five minutes. There’s no good reason not to do this immediately.

What You Actually Save

I’m still surprised by how many teams skip this step — especially when the savings kick in immediately. If your ECS containers are pulling Docker layers from ECR (which stores layers in S3) or your Lambda functions are reading configuration from S3, that traffic has been flowing through NAT and costing $0.045 per GB. A Lambda function reading from S3 1,000 times a day at 1MB per read is 30GB a month — $1.35 just for those calls. Multiply across all your functions and containers, and this endpoint typically saves teams 30–50% of their total NAT cost, for zero ongoing expense.

One real gotcha — verify the endpoint policy after creation. By default it allows full access to S3 across all buckets. For production, tighten that to only the buckets your workloads actually need. Small JSON policy, ten minutes to write properly. Don’t make my mistake of leaving it wide open for six months.

Interface VPC Endpoints for Other AWS Services

Gateway endpoints only exist for S3 and DynamoDB. For everything else — CloudWatch Logs, ECR API, STS, SQS, SSM, Secrets Manager — you need Interface VPC Endpoints, which are a different beast entirely, with actual costs attached.

An Interface Endpoint creates an Elastic Network Interface in your subnet with a private IP. Traffic to the supported AWS service routes to that ENI instead of out through NAT. Pricing is $0.01 per hour per AZ plus $0.01 per GB processed. Per-AZ cost works out to $7.20/month in hourly charges — so in three AZs, that’s $21.60/month in base charges per endpoint. Wait. That’s more than half of one NAT Gateway’s hourly cost, just for a single interface endpoint. The math here requires some care.

When Interface Endpoints Actually Save Money

The calculation depends entirely on your data volumes and which services you’re hitting. Take CloudWatch Logs. If your ECS tasks are generating 100GB of log data per month flowing through NAT Gateway, you’re paying $4.50/month just in NAT data processing for logs. Does that traffic justify a $21.60/month interface endpoint? Honestly, no — not in isolation. Interface endpoints make sense when you combine several high-volume services and calculate whether the aggregate endpoint cost undercuts your total NAT cost.

The services most worth considering:

• ECR API and ECR DKR — if you’re pulling container images frequently in ECS or EKS, image layers get large fast. 200GB of image pulls per month costs $9.00 in NAT data processing alone
• CloudWatch Logs — high-volume logging workloads generate surprising data at scale
• SSM and Secrets Manager — lower volume, but these are security-sensitive services where keeping traffic off the public internet has independent value beyond pure cost savings
• SQS — worth the analysis if you’re running high-throughput queue-based architectures

The Diminishing Returns Problem

Here’s what experience has actually taught me. The first one or two interface endpoints you add — targeting your highest-volume services — will likely pay for themselves. The third and fourth require careful volume analysis. By the fifth or sixth, you’re probably spending more on endpoint costs than you’d save on NAT, unless your traffic volumes are substantial. I’ve seen teams over-engineer this and end up paying more than before. Set up the gateway endpoints first. Then pull three months of NAT Gateway data processing costs from Cost Explorer, filter by usage type, identify which AWS services generate the most traffic, and build the business case from actual numbers before touching interface endpoints.

NAT Instance as a Budget Alternative

Frustrated by a $150/month NAT Gateway bill with no immediate path to refactoring the application, plenty of teams have turned to the NAT Instance using nothing more exotic than a small EC2 instance and a modified route table. It’s old-school — predates managed NAT Gateway — and AWS’s own documentation treats it as a legacy option. But for specific use cases, particularly dev and staging environments, the economics are hard to argue with.

A NAT Instance is just an EC2 instance running NAT software that you manage yourself. Disable source/destination checking on the instance, update the routing tables to point at it, and traffic flows through it the same way it would through a managed gateway. Simple concept. Genuinely cheap.

The Cost Comparison

An arm64 t4g.nano instance in us-east-1 costs $0.0042 per hour — $3.02 per month. Compare that to $32.40 per month for a single NAT Gateway. You can run a NAT Instance for a full year for less than what one NAT Gateway costs in a single month. For a dev environment with light traffic — three developers, some integration tests, maybe 20GB of data processed per month — the numbers look like this:

• NAT Gateway — $32.40 (hourly) + $0.90 (data) = $33.30/month
• t4g.nano NAT Instance — $3.02 (hourly) + $0.90 (data, same rate) = $3.92/month

Roughly $29 saved per environment per month — $348/year just in dev. If you have dev, staging, and a preview environment, you’re looking at over $1,000/year from switching non-production environments to NAT Instances. That’s real money before a Series A.

The Real Trade-offs — Don’t Skip This Part

Managed NAT Gateway charges a premium for reasons that genuinely matter in production. NAT Instances don’t auto-scale — that t4g.nano handles a limited number of concurrent connections, and if you spike, traffic drops. The instance itself is a single point of failure. NAT Gateway is redundant by design inside each AZ. You also manage patching, monitoring, and recovery yourself. At minimum: set up a CloudWatch alarm on network throughput and instance status checks, use a launch template so you can quickly replace a failed instance, and keep your NAT Instance in a dedicated security group with tight outbound rules.

For production traffic that actually matters — transactional systems, customer-facing APIs, anything where a five-minute outage costs real money — a NAT Instance probably isn’t worth the operational risk. For dev, staging, preview environments, internal tooling, batch processing with tolerant SLAs — the $3/month instance is perfectly reasonable. The fck-nat project on GitHub, apparently, provides a clean maintained setup script using standard Amazon Linux 2023 that runs well on t4g instances and costs nothing beyond the instance itself. Worth bookmarking.

Putting It Together — A Decision Framework

The path through this isn’t complicated once you see it laid out.

1. Create Gateway VPC Endpoints for S3 and DynamoDB immediately. Zero cost, guaranteed savings, no downside. First thing you should do in any VPC with private subnets — at least if you’re touching S3 or DynamoDB at all, which almost everyone is.
2. Pull NAT Gateway data processing costs from Cost Explorer. Identify which AWS services are generating the most traffic. If ECR or CloudWatch Logs dominate, model whether Interface VPC Endpoints break even at your actual volumes before you create them.
3. Audit your non-production environments. Any environment where high availability isn’t truly required is a candidate for a t4g.nano NAT Instance. The savings compound fast across multiple environments.
4. Consider whether some workloads need public internet access at all. Lambda functions that only talk to S3, DynamoDB, and SQS through VPC endpoints don’t need a NAT Gateway in their VPC configuration — removing it entirely might be the right call.

The mistake I made early on was treating AWS architecture as a given — one NAT Gateway per AZ, always, everywhere. Reasonable production default in a mature system. Expensive default to copy-paste into every environment without thinking. Spending thirty minutes on this analysis has saved teams I’ve worked with anywhere from $100 to $600 a month. Don’t make my mistake — check the bill before it checks you.