Bandwidth overage is the line item that turns a $5 VPS into a $60 invoice. Unlike RAM or CPU, which are capped and simply throttle or crash, transfer is usually metered and billed after the fact — so a single misconfigured backup job or an un-cached video can consume a month of allowance in a weekend. This guide explains exactly how per-GB bandwidth billing works and how to keep it from surprising you.
What “1 TB Included” Actually Includes
The headline allowance is almost never the whole story. Four accounting models dominate budget hosting, and they produce bills that differ by 2–4× for identical traffic.
| Billing model | What counts | Best for | Risk |
|---|---|---|---|
| Egress only | Outbound bytes only | Websites behind a CDN | Low — inbound is free |
| Egress + ingress | Both directions | Backup targets, VPNs | High — usage doubles |
| 95th percentile | Top 5% of samples discarded | Steady streaming | Spikes raise the rate |
| Unmetered at port speed | Bytes free, speed capped | Heavy transfer | Port cap limits throughput |
The first question to ask any provider is which model they use. The second is what happens when you exceed the allowance: does the port throttle to 1–10 Mbps, does billing continue at a per-GB rate, or does the service suspend? Suspension is the friendliest outcome for your wallet and the worst for your site.
Per-GB Overage Rates and What They Really Cost
Overage rates on budget plans commonly land between $0.005 and $0.05 per GB. That range looks trivial per gigabyte and is enormous across a month, because a single unbounded service can move terabytes.
| Overage rate | Cost per extra 100 GB | Cost per extra 1 TB | Cost per extra 5 TB |
|---|---|---|---|
| $0.005/GB | $0.50 | $5 | $25 |
| $0.01/GB | $1.00 | $10 | $50 |
| $0.02/GB | $2.00 | $20 | $100 |
| $0.05/GB | $5.00 | $50 | $250 |
At $0.05/GB, a 5 TB overage costs more than an entire year of a $5 plan. This is why the arithmetic is worth doing before you choose a provider: a plan that includes 500 GB more transfer for $2 more per month is almost always cheaper than paying overage on the smaller plan. Our comparison of how much bandwidth a small VPS actually needs gives baseline traffic figures to size against.
The Five Workloads That Blow Through Allowances
- Un-cached video or audio. One hour of 1080p streaming is roughly 1.5–3 GB per viewer. Twenty concurrent viewers can exhaust 1 TB in under three days.
- Remote backups pulled to another host. A nightly full backup of 40 GB, pulled rather than pushed incrementally, is 1.2 TB per month on its own.
- Torrent or mirror seeding. Seeding runs at whatever your port allows, 24 hours a day, with no natural ceiling.
- An open proxy or misconfigured caching layer. A forgotten Squid, Redis, or Docker registry proxy can be discovered and abused within days.
- Bot traffic with no rate limiting. Aggressive crawlers pulling full page payloads repeatedly add up far faster than human traffic.
The common thread is a service that transfers data without a built-in budget. Anything that can saturate a 1 Gbps port for 24 hours moves roughly 10 TB in a day, so the gap between “included” and “catastrophic” is measured in hours, not weeks.
Configuring Alerts Before You Exceed the Allowance
The only reliable defence is measurement at the source. Most providers expose a bandwidth graph in their control panel, but it lags by hours and rarely alerts. Track it yourself.
| Tool | What it measures | Alert threshold to set |
|---|---|---|
| vnstat | Per-interface monthly totals | 50%, 75%, 90% of allowance |
| provider API | Billable egress as the host counts it | Daily poll, alert on 5%/day pace |
| iftop / nethogs | Live per-process transfer | Manual, for diagnosing spikes |
| nginx access logs | Bytes served per path | Flag any single path > 5% of total |
| Cloudflare analytics | Cache hit ratio and origin egress | Alert if hit ratio drops below 70% |
The provider’s own count is authoritative for billing, your local count is authoritative for debugging. Watch both. A widening gap between them usually means the provider counts ingress or measures at a different point in the network stack than you assumed.
Reducing Overage Without Losing Performance
- Put a CDN in front of all static assets and cache aggressively — this typically removes 60–90% of origin egress.
- Switch backups from full pulls to incremental pushes with compression and deduplication.
- Cap per-IP and per-connection bandwidth with tc or a reverse proxy rule.
- Compress everything: Brotli for text, modern formats (AVIF/WebP) for images.
- Rate-limit bot traffic at the web server and serve crawlers a lighter payload.
- For workloads that are inherently transfer-heavy, choose an unmetered or 95th-percentile plan instead of paying per gigabyte.
Applied in that order, most sites cut billable egress by more than half within a week, which usually puts them back inside the included allowance. If they still cannot fit — media hosting, game distribution, large file mirrors — the correct answer is a different billing model, not more discipline. Compare budget VPS plans by transfer allowance on our site, and check our notes on hourly versus monthly billing granularity if your traffic is bursty rather than steady.
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