Egress and data transfer costs, IP addresses and load balancers on cloud bills

Egress is data leaving a cloud provider's network: pages and files sent to your visitors, downloads to your office, backups copied to another provider, replication to another region. Public clouds usually charge for it per GB above a free allowance, while inbound data is usually free. Traffic between availability zones or regions inside the same provider can also be charged. Around it sit networking lines that look small but run all month: public IPv4 addresses, load balancers, NAT gateways and VPN connections. Together these are the most commonly under-estimated part of a cloud bill.

This guide belongs to the pricing overview. Rates below are illustrative; real rates depend on provider, region, destination and volume.

The kinds of data transfer

Transfer	Usually charged?	Example
Internet to the cloud (ingress)	Usually free	Uploading files, visitors submitting forms
Cloud to internet (egress)	Yes, per GB above an allowance, often tiered	Serving web pages, video, downloads
Between availability zones in one region	Often, per GB each way	A web server in one zone calling a database in another
Between regions of the same provider	Yes, per GB	Replicating backups from Montreal to Toronto
Through a NAT gateway	Hourly fee plus per GB processed	Private servers downloading updates
To a CDN	Varies; sometimes reduced or free from origin	Caching website images closer to users
VPS or dedicated plan	Monthly allowance included, overage per GB or speed cap	A VPS with a stated transfer quota

Many VPS and dedicated plans include a generous transfer allowance in the monthly price. Public clouds itemise it. That difference alone can reverse which option looks cheaper for a traffic-heavy site.

Estimating your egress

Find your current outbound traffic. Your current host's control panel, your web analytics (page views × average page size) or your CDN reports.
Add other outbound flows: backups copied off-site, API responses to partners, file downloads by staff working remotely.
Subtract what a CDN will serve from its cache, if you use one, and add what the CDN pulls from your origin.
Multiply by the per-GB rate for the tier and destination.

Illustrative example. An online store has 40,000 page views a month at about 2.5 MB each, plus 150 GB of product image downloads and 100 GB of off-site backup copies.

Pages: 40,000 × 2.5 MB = 100,000 MB, about 100 GB
Images: 150 GB
Backups: 100 GB
Total: 350 GB a month
Free allowance: an illustrative 100 GB, leaving 250 GB billable
At an illustrative $0.12 per GB: 250 × $0.12 = $30 a month

If a new marketing video brings 1 TB of extra downloads, the line grows by 1,000 × $0.12 = $120 a month. That is why media-heavy sites often serve large files through a CDN or a provider with included transfer.

Public IP addresses

IPv4 addresses are scarce, and several large providers now charge for each public IPv4 address per hour, whether attached to a running server or not. Some VPS plans include one address and charge for extras.

Illustrative example. Four public IPv4 addresses at an illustrative $0.007 an hour each: 4 × $0.007 × 730 hours = $20.44 a month. Releasing two that are no longer used saves about $10 a month.

Ways to reduce IP costs: put several services behind one load balancer or reverse proxy, use private addresses inside the network, release unused elastic or static IPs, and use IPv6 where your users and tools support it.

Load balancers and NAT gateways

A load balancer spreads traffic across servers and is needed for redundancy. It is usually billed per hour it exists plus a usage charge (connections, rules or data processed). A small business with one web server may not need one; a business that needs to survive a server failure usually does.

A NAT gateway lets private servers reach the internet for updates without public addresses. It is billed per hour plus per GB processed, which can surprise teams that route large downloads through it.

Illustrative monthly networking lines for a two-server application:

Line	Illustrative monthly cost (CAD)
Load balancer, base hours	$25
Load balancer usage	$8
NAT gateway, base hours	$45
NAT data processed, 200 GB at $0.06	$12
Two public IPv4 addresses	$10
Total networking	$100

In this example the networking lines cost about as much as a small VM. Some designs avoid a NAT gateway entirely, for example by using provider endpoints for updates or by running a small proxy.

Egress at exit

Leaving a provider means copying all your data out, which is egress too. Some providers have announced reduced or waived egress for customers who are leaving, usually on request and with conditions. Read the current terms before you plan a move; see migration and exit costs.

Controls that work

Put a CDN in front of public websites and cache images and downloads.
Keep chatty components (web and database) in the same zone unless you need cross-zone redundancy, and know what the redundancy costs.
Compress responses and images.
Set a budget alert on data transfer; see cost control with budgets and tagging.
Review IP addresses and NAT gateways quarterly.

FAQ

Why is uploading to the cloud free but downloading charged?

Providers generally do not charge for inbound traffic and do charge for outbound. Whatever the business reason, the effect for you is that serving, replicating and exporting data cost money, while importing does not.

Does traffic between my two cloud servers cost anything?

It depends on where they are. Within the same zone it is often free; across zones or regions it is often charged per GB. Check the provider's data transfer page for your region.

Is a VPS "unmetered" plan really unlimited?

Usually it is limited by port speed and an acceptable-use policy. Read both; sustained heavy use can lead to throttling or a request to upgrade.

Sources

Competition Bureau Canada — advertised prices and fixed obligatory fees
Canadian Centre for Cyber Security — network security in cloud deployments
Canada Revenue Agency — GST/HST on cloud services