What Are Egress Fees? How Download Charges Work in Storage

Egress fees are charges for data that leaves a storage provider's network, usually priced per gigabyte downloaded. On AIOZ Storage the documented rate is 0.005 USD per GB downloaded, and the billing docs list no bandwidth charge for uploads. Here you will see what triggers egress, how to estimate it, and what the docs leave out.

TL;DR:

• Egress fees bill the data you read out of storage, so they follow how often and by whom your files are accessed, not how much you keep.
• AIOZ Storage charges 0.005 USD per GB downloaded plus 0.017 USD per GB per month for storage, both calculated hourly from a pre-paid balance.
• At those rates, the bandwidth charge equals the storage charge when you download 3.4 times the amount you store each month.
• The billing docs do not say whether API requests are billed, whether any free allowance exists, or how a "GB" is defined.

What Are Egress Fees?

Egress is outbound traffic: bytes that move from the provider's servers to a user, an application, or another cloud. An egress fee is the price a provider puts on those bytes, usually a rate per GB that is summed over a month.

Many providers treat inbound traffic differently, and Amazon's S3 pricing page lists data transferred in from the internet as free. It also gives the first 100 GB per month out to the internet as free, aggregated across AWS services and regions, and you pay by the GB past that.

Why Providers Charge for Egress

Two reasons come up in provider and vendor material, and the first is cost recovery: outbound traffic uses network capacity that the provider pays for. The second is retention: free uploads and paid downloads make it expensive to move a large dataset elsewhere. A CDN vendor, Edge Network, calls egress a switching cost for exactly that reason.

Treat the second point as a competitor's view, since it describes an incentive and the providers in question do not state it as their pricing logic.

What Triggers Egress Charges?

Any read that sends bytes out of the provider's network can count. The Edge Network guide lists several cases, and the same patterns apply to any object store:

• Serving files to end users.
• Moving data to another cloud or provider.
• Pulling data back to your own servers, including restores.
• Page views and downloads that fetch stored assets.

The Edge Network guide sums this up as egress being driven by your users' behaviour. That makes it harder to predict than storage, because you control how much you store, but your users control how often they read it.

How AIOZ Storage Charges for Bandwidth

The AIOZ Storage billing docs describe two charges for regular object storage. Bandwidth is charged when you download data, and storage is charged on an hourly basis for the space you use, at the prices on the live billing page:

A few more rules from the docs matter for planning:

• Every hour, AIOZ calculates your usage: the bandwidth you used for downloads and the storage occupied at that moment.
• Billing is pre-paid. You deposit funds first, and there is no free plan.
• A sub-user's usage is billed together with the root account.
• The Overview page says AIOZ Storage's built-in CDN delivers data from the nearest node "without needing extra fees for separate CDN services".

Because the model is pre-paid, a balance that falls too low locks the account. How AIOZ Storage Pricing Works covers the minimum balance and the 3-day deadline in detail.

How Do I Estimate My Egress Bill?

Multiply the GB you expect to download in a month by the bandwidth rate, then add storage. Using the documented rates and treating 1 TB as 1,000 GB (the docs do not define the unit):

The ratio between reads and stored data decides which bill dominates, because storage costs 0.017 USD per GB-month and bandwidth costs 0.005 USD per GB. The two are equal when you download 0.017 / 0.005 = 3.4 times your stored data each month. Below that ratio storage is the larger charge, and above it bandwidth is.

Here is a small estimator you can adapt, which uses only the two rates above and prints the example in the chart:

STORAGE_USD_PER_GB_MONTH = 0.017  # AIOZ billing docs, charged hourly
BANDWIDTH_USD_PER_GB = 0.005      # AIOZ billing docs, per GB downloaded

def monthly_estimate(stored_gb, downloaded_gb):
    storage = stored_gb * STORAGE_USD_PER_GB_MONTH
    bandwidth = downloaded_gb * BANDWIDTH_USD_PER_GB
    return storage, bandwidth, storage + bandwidth

storage, bandwidth, total = monthly_estimate(stored_gb=10_000, downloaded_gb=30_000)
print(f"storage {storage:.2f} USD, bandwidth {bandwidth:.2f} USD, total {total:.2f} USD")
# storage 170.00 USD, bandwidth 150.00 USD, total 320.00 USD

Storage is charged on the space occupied each hour, so a bucket that grows during the month costs less than its final size suggests. Treat the estimator as a ceiling for a bucket that stays full all month.

Ways to Keep Egress Down

These are general practices, not AIOZ features, and they apply to any provider that bills for downloads:

1. Cache what many people read. Put popular files behind a cache so repeated reads do not each cross the provider's network.
2. Send smaller files. Compress text, resize images, and serve a lower video rendition when the screen is small.
3. Fetch only the bytes you need. The S3 API allows a ranged GET for part of an object. AIOZ's docs do not say whether the endpoint supports it, so test before relying on it.
4. Stop re-downloading in pipelines. A job that pulls the same dataset on every run pays for it every run. Cache it on the runner.
5. Watch the Billing tab. The AIOZ billing tutorial describes a Bandwidth section showing total bandwidth charges and usage for the billing cycle. Check it after any change that increases reads.

What the AIOZ Docs Do Not Say

I read the billing, overview and penalty pages and found these gaps, which you should treat as unknown until AIOZ states them:

• Upload bandwidth. The docs say bandwidth is charged on download. They do not say in so many words that uploads are free, but they list no upload charge for regular storage.
• Request fees. The docs list no per-request charge for regular object storage. The vector database is different, because it charges per query.
• Free allowance. No free plan exists, and the docs do not describe a monthly free amount of bandwidth.
• What counts as a downloaded GB. The docs do not say whether partial reads, failed requests or response headers are counted, or whether a GB means 10^9 or 2^30 bytes.
• Region differences. The billing page lists one bandwidth price and no regional variations.

If a number matters for a budget, ask AIOZ support to confirm it before you commit.

Frequently Asked Questions

What are egress fees in cloud object storage, and why do providers charge them?
Egress fees are charges for data that leaves the provider's network, such as a download, a restore, or a transfer to another cloud, and they are normally priced per GB.

Does AIOZ Storage charge egress fees for downloads from a bucket?
Yes, because the billing docs list bandwidth as a charge incurred when you download data, at 0.005 USD per GB downloaded.

Is uploading data to AIOZ Storage charged as bandwidth in the same way?
The billing docs describe bandwidth charges for downloads only, and they list no upload bandwidth charge for regular object storage.

Does AIOZ Storage bill per request when you list, read or write objects?
The billing docs list no per-request charge for regular object storage, although a separate rate limit of 100 requests per second applies, and the vector database does charge per query.

How much does it cost to download 10 TB from AIOZ Storage?
About 50 USD at the documented rate, if 1 TB is 1,000 GB. The docs do not define the unit, so the exact figure may differ slightly.

Are egress fees the same thing as CDN fees when you serve files to users?
Not always, since a CDN usually bills its own delivery separately. AIOZ's Overview page says its built-in CDN delivers data from the nearest node without extra fees for a separate CDN service, but the bandwidth charge still applies to downloads.

Related Reading

• How AIOZ Storage Pricing Works: Storage and Delivery Costs - the full rate card, hourly billing and the minimum balance rule.
• What Is a CDN and How Does It Relate to Object Storage? - where cached delivery sits in front of a bucket.
• Hot vs Cold Storage: Storage Tiers and When They Matter - the other cost lever that multi-tier providers add.
• How to Create a Bucket and Upload a File on AIOZ Storage - the setup steps, including adding credits.
• AIOZ Storage Vector Database Pricing: What You Pay For - the per-query charges that regular storage does not have.
• When decentralized video delivery costs less than a CDN: the same delivery cost question from the video side, on AIOZ Stream.

References

• AIOZ Storage Docs: Billing
• AIOZ Storage Docs: Overview
• AIOZ Storage Docs: Manage Billing
• Amazon S3 Pricing
• Edge Network: Zero Egress Explained