AWSAWS Transfer FamilyStorage

`aws_transfer_server` cost estimation

Managed SFTP, FTPS, or FTP access to S3 and EFS. Priced per protocol-hour the endpoint is enabled, plus per-GB uploaded and downloaded.

An aws_transfer_server provides managed file transfer (SFTP, FTPS, FTP, or AS2) backed by S3 or EFS, so you don't run and patch your own file-transfer servers. The cost has a standing component and a usage component.

The standing cost is per protocol-hour: each enabled protocol on the endpoint bills around $0.30/hour, roughly $219/month per protocol, billed continuously whether or not anyone connects. An endpoint with both SFTP and FTPS enabled is two protocol-hours. On top of that, data uploaded and downloaded through the server bills per GB (around $0.04/GB each direction).

c3x prices the protocol-hours from the enabled protocols at 730 hours/month and treats data transfer as usage-based, supplied in c3x-usage.yml. The always-on protocol-hour is the surprise: a lightly-used SFTP endpoint still costs ~$219/month, so consolidating users onto one endpoint rather than provisioning many is the main lever. The backing S3 bucket or EFS file system bills separately.

Terraform example

A minimal but realistic configuration that C3X can estimate.

resource "aws_transfer_server" "sftp" {
  endpoint_type = "PUBLIC"
  protocols     = ["SFTP"]
  domain        = "S3"

  identity_provider_type = "SERVICE_MANAGED"

  tags = {
    Name = "partner-sftp"
  }
}

Pricing dimensions

What you actually pay for when you provision aws_transfer_server.

Dimension	Unit	What's being charged
Protocol hours	per protocol-hour	Each enabled protocol (SFTP/FTPS/FTP/AS2) billed continuously while the endpoint is up. c3x prices the protocol count at 730 hours/month. $0.30/hour per protocol (~$219/month)
Data uploaded	per GB	Data uploaded through the server. Usage-based; define in c3x-usage.yml. $0.04/GB uploaded
Data downloaded	per GB	Data downloaded through the server. Usage-based. $0.04/GB downloaded

Sample C3X output

Example output from c3x estimate (SFTP only, endpoint cost):

aws_transfer_server.sftp
└─ Protocol hours (SFTP)        730  protocol-hours    $219.00

OVERALL TOTAL                                          $219.00
(data transfer & backing S3 billed separately)

Optimization tips

Common ways to reduce aws_transfer_server cost without changing the workload.

Consolidate users onto one endpoint

Per avoided endpoint

Each server (and each protocol on it) bills continuously. Many users can share one endpoint with per-user home directories, far cheaper than one endpoint per partner.

Enable only the protocols you need

~$219/month per protocol

Each enabled protocol is a separate ~$219/month charge. If partners only use SFTP, don't also enable FTPS and FTP.

Consider direct S3 access for internal transfers

Whole endpoint for internal use

For internal or programmatic transfers, the S3 API or presigned URLs avoid the Transfer Family endpoint entirely. Reserve managed SFTP for external partners that require the protocol.

FAQ

How does c3x estimate Transfer Family cost?

It prices the protocol-hours from the enabled protocols (protocols list) at 730 hours/month. Upload and download data are usage-based and supplied in c3x-usage.yml. The backing S3/EFS bills as its own resource.

Why does an idle SFTP server cost ~$219/month?

Transfer Family bills per enabled protocol-hour continuously while the endpoint exists, independent of connections or transfers. Only the data-transfer charges scale with usage.

Does each protocol cost separately?

Yes. Enabling SFTP and FTPS on one server is two protocol-hour charges (~$438/month combined). Enable only the protocols your users actually need.

Is the S3 storage included?

No. The S3 bucket (or EFS file system) the server reads and writes bills separately for storage and requests. c3x estimates it as its own resource.

How can I reduce the cost of a low-traffic endpoint?

Consolidate multiple users or partners onto a single endpoint with isolated home directories, and enable only required protocols. The standing protocol-hour cost dominates for low-traffic servers.