Running & Maintaining a Site

Egress Fee

Definition

An egress fee is what a host or cloud provider charges for outbound data transfer, billed per gigabyte sent from their network to the internet. The asymmetry catches people out: putting data in is almost always free, taking it out is the metered direction, and that covers both the ordinary traffic of people reading your site and the one-off cost of copying everything to a different provider. Pricing takes several shapes. Some hosts include transfer in a flat plan price and charge nothing extra, some give a monthly allowance and meter everything above it, and some meter from the first byte at rates that step down by volume and vary by region. What is counted is the response body plus headers, after compression, so a page that gzips from 300 KB to 80 KB is billed at roughly 80 KB. Because the bill is file size multiplied by number of downloads, the same object storage bucket can cost almost nothing for a year and then produce a startling invoice in a single week.

Why It Matters

Transfer is the line item that grows with success, which is why it surprises people. Work one through: a 4 MB PDF fetched fifty thousand times is about 200 GB of egress, and published rates sit anywhere from a few pence per gigabyte to nothing at all, depending entirely on which pricing shape you signed up to. On an included-transfer plan that 200 GB is free; on a metered one it is a real invoice line. That spread is why the cost per gigabyte is worth reading before a file goes anywhere popular. Rates also change and differ by region and volume tier, so treat any figure you read, this one included, as a reason to check the current rate card rather than as a quote.

How It Works

Every HTTP response your host sends is measured and added to a running monthly total, usually sampled at the edge or load balancer rather than at the origin. Range requests count only the bytes actually sent, so a video someone scrubs through partially costs less than the whole file. A CDN changes the arithmetic in two places: cache hits are served from the edge and may be billed at a different rate to origin transfer, and a cached object is pulled from origin once per location rather than once per visitor. Compression acts directly on the bill — Brotli or gzip on text assets often cuts billable volume by two thirds, and converting images to WebP or AVIF cuts it further. Providers show the running total in a usage dashboard with a day or two of lag, which is easily long enough for a bad weekend to finish before you see it.

Real-World Example

A firm publishes its 4 MB annual report at yearbook.99helpers.site/report.pdf and links it from a press release. The release gets picked up, and the PDF is fetched about fifty thousand times over ten days — close to 200 GB out. Re-exporting the same document at screen resolution brings it to 1.1 MB with no visible difference, which would have made the same traffic spike roughly 55 GB. Where transfer is included in the plan neither number is a bill; where it is metered, the difference is most of the cost.

Common Mistakes

  • Budgeting from storage size rather than transfer — a 4 MB file costs almost nothing to keep and can cost a hundred times that to serve in one busy week
  • Assuming a free tier covers transfer because it covered storage — the two allowances are separate, and the transfer one is the one that runs out
  • Leaving a print-resolution PDF or an unresized image as the download everyone clicks — the bill is file size times downloads, and only one of those two is under your control

Related Terms

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