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

The AWS NAT Gateway cost alternative conversation comes up every single time a startup founder sees their first real AWS bill. I’ve been there. I was running a small SaaS product, we had maybe 200GB of outbound traffic a month, and I genuinely could not figure out why our AWS bill kept climbing past what I expected. Took me two hours of cost explorer drilling to find it. NAT Gateway. Three of them, one per availability zone, quietly billing me every hour whether I used them or not. That moment of recognition — equal parts embarrassing and expensive — is apparently a rite of passage in the AWS world.

This article is a practical breakdown of what NAT Gateway actually costs, and four concrete alternatives that can cut that line item dramatically. Real numbers, not ballpark estimates. If you’re running any workload where Lambda functions, ECS tasks, or EC2 instances 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 the reason nobody sees it coming. NAT Gateway charges you on two dimensions: an hourly rate per gateway, and a per-gigabyte data processing fee on top of that.

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

Here’s where startups get caught. AWS Well-Architected Framework recommends deploying resources across multiple availability zones for resilience. That’s genuinely good advice. But most people implement this pattern — private subnets in three AZs, one NAT Gateway per AZ — without thinking hard about the cost multiplier. Three NAT Gateways means three times the hourly fee. At 500GB of data processed per month across those three gateways, you’re looking at something 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 a month easily. That’s not a catastrophic number for a funded startup. But here’s what 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 it 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 without realizing it. The dev environment NAT Gateways were essentially idle, processing maybe 20GB a month, but the hourly meter never stops.

The other trap is that NAT Gateway doesn’t appear as a single line item that screams “look at me.” It shows up under EC2 service charges, often split across data transfer categories. Easy to miss until you build a cost allocation tag strategy or use Cost Explorer filtered by usage type.

Gateway VPC Endpoints — Free for S3 and DynamoDB

Probably should have opened with this section, honestly. 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.

The way they work is conceptually simple. Instead of routing traffic from your private subnet out through NAT Gateway and over the public internet to reach S3 or DynamoDB, a Gateway Endpoint adds a route to your route table that sends that traffic directly through AWS’s internal network. The traffic never leaves the AWS backbone. Faster, free, and arguably more secure.

Setting Up a Gateway VPC Endpoint for S3

In the AWS Console, go to 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 the private subnets where your workloads run. Hit create.

That’s the whole setup. 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 goes through the endpoint instead of NAT Gateway.

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.

What You Actually Save

Surprised by how many teams skip this step, especially when the savings are immediate. 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 you $0.045 per GB. A Lambda function reading from S3 1,000 times a day at even 1MB per read is 30GB a month. That’s $1.35 just for those Lambda calls. Multiply across all your functions and containers, and this endpoint typically saves teams 30–50% of their total NAT cost immediately, for zero ongoing cost.

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. It’s a small JSON endpoint policy and takes ten minutes to write properly.

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 with actual costs attached.

An Interface Endpoint creates an Elastic Network Interface in your subnet with a private IP address. Traffic to the supported AWS service routes to that ENI instead of out through NAT. The pricing is $0.01 per hour per AZ plus $0.01 per GB of data processed. Per AZ cost works out to $7.20/month in hourly charges, plus data processing. 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. So this math requires some care.

When Interface Endpoints Actually Save Money

The calculation depends entirely on your data volumes and how many services you’re hitting. Consider CloudWatch Logs. If your ECS tasks are generating 100GB of log data per month, and that traffic currently flows through NAT Gateway, you’re paying $4.50/month just in NAT data processing fees for logs. Add the $32.40 hourly contribution and the question becomes: does this traffic represent enough of your total NAT load to justify a $21.60/month interface endpoint?

The honest answer for most teams — no, not in isolation. Interface endpoints make sense when you combine several services together and calculate whether the aggregate endpoint cost undercuts your NAT cost.

The services most worth considering for interface endpoints:

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

The Diminishing Returns Problem

Here’s what experience has taught me about this approach. 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.

Shocked by how often teams over-engineer this and end up paying more. Set up the gateway endpoints first. Then pull three months of NAT Gateway data processing costs from Cost Explorer, filter by usage type to see data volumes, identify which AWS service endpoints would see the most traffic, and build the business case from actual numbers before creating interface endpoints.

NAT Instance as a Budget Alternative

Cornered by a $150/month NAT Gateway bill with no immediate path to refactoring the application to use VPC endpoints, plenty of teams have turned to the NAT Instance as a stopgap. 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. You disable source/destination checking on the instance, set up the routing tables to point at it, and traffic flows through it like a managed NAT Gateway.

The Cost Comparison

An arm64 t4g.nano instance in us-east-1 costs $0.0042 per hour. Monthly that’s $3.02. 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 — let’s say 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

Savings — roughly $29/month per environment, or $348/year just in dev. If you have dev, staging, and a preview environment, you’re looking at over $1,000/year in savings from switching dev-tier environments to NAT Instances.

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

The managed NAT Gateway charges a premium for reasons that matter in production. NAT Instances have no auto-scaling. That t4g.nano instance can handle a limited number of concurrent connections. If you spike, traffic drops. The instance itself is a single point of failure — it goes down, your private subnet loses internet access. NAT Gateway is redundant by design inside each AZ.

You also manage patching, monitoring, and recovery. Set up a CloudWatch alarm on network throughput and instance status checks, at minimum. Use a launch template so you can quickly replace the instance if it fails. Keep your NAT Instance in a dedicated security group with tight outbound rules.

For production traffic that matters — transactional systems, customer-facing APIs, anything where a five-minute outage costs real money — NAT Instance probably isn’t worth the operational risk. For dev, staging, preview environments, internal tooling, batch processing workloads with tolerant SLAs — the $3/month instance is perfectly reasonable.

One approach that works well is AMIs from the AWS Marketplace that come pre-configured for NAT, though honestly the fck-nat project on GitHub provides a clean, maintained setup script using standard Amazon Linux 2023 that runs well on t4g instances and costs nothing beyond the instance itself.

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. This should be the first thing you do in any VPC that has private subnets.
2. Pull your NAT Gateway data processing costs from Cost Explorer. Identify which AWS services are generating the most traffic through NAT. If ECR or CloudWatch Logs dominate, model whether Interface VPC Endpoints break even at your volumes.
3. Audit your non-production environments. Any environment where high availability isn’t truly required is a candidate for switching to a t4g.nano NAT Instance. The savings compound across multiple environments.
4. Consider whether some workloads need to reach the public internet 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.

The mistake I made early on was treating the AWS architecture as a given — one NAT Gateway per AZ, always, everywhere. That’s a reasonable production default in a mature system. It’s an 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. That’s real money, especially before a Series A.