Hosting & Server Tools
Capacity, uptime and cost maths for people who run servers.
Hosting decisions turn on a handful of numbers that are rarely presented clearly: how much bandwidth a given traffic level actually consumes, what an uptime guarantee permits in real minutes, and what a server costs per account once licences and support time are counted.
These calculators exist because the marketing figures and the operational figures are usually different, and the gap between them is where margin quietly disappears.
- Uptime & SLA Calculator Convert an uptime percentage into the downtime it allows per day, week, month, quarter and year.
- Bandwidth Calculator Estimate monthly data transfer from visits, pages per visit and page weight, with headroom and growth projection.
- Server Cost Per Account Calculator Work out what each hosting account really costs once licences and overhead are counted, plus lifetime value.
Capacity and cost, for people who run the servers
Three calculators for questions that come up when you are the one answering for the infrastructure: how much downtime does that SLA actually permit, how much transfer will this site consume, and what does an account cost once everything is counted.
What an uptime percentage really allows
Uptime is quoted in a format designed to sound reassuring. Converting it to time is clarifying:
| Uptime | Downtime per month | Per year |
|---|---|---|
| 99% | 7 hours 18 minutes | 3 days 15 hours |
| 99.9% | 43 minutes | 8 hours 45 minutes |
| 99.95% | 21 minutes | 4 hours 22 minutes |
| 99.99% | 4 minutes | 52 minutes |
The gap between 99% and 99.9% is the difference between an afternoon offline and a coffee break. The Uptime & SLA Calculator does this for any figure and any period.
Worth knowing before you rely on one: most SLAs measure availability monthly, exclude scheduled maintenance, and compensate in service credits rather than money. A 99.9% guarantee typically means that if it is breached you may claim back a fraction of that month's fee — not that the downtime will not happen.
Estimating bandwidth without guessing
The Bandwidth Calculator works from visits, pages per visit and average page weight. The figure people underestimate is page weight: a modern page with a hero image, a web font and a video embed is several megabytes, not the few hundred kilobytes the HTML suggests.
Add headroom. Traffic is not evenly distributed — a mention on a large site or a seasonal peak can put a month's typical transfer through in a day. Sizing to your average leaves nothing for the week that matters.
What an account actually costs
The Server Cost Per Account Calculator exists because the obvious calculation — server price divided by accounts — leaves out most of the cost. Control panel licences, backup storage, monitoring, security tooling and the support time each account consumes are all real and all recurring.
The output that usually changes a decision is lifetime value against acquisition cost. An account acquired for less than it returns over its life is a good account even at a thin monthly margin; one acquired for more is a loss that scales with every new signup.
Common questions
How much downtime does 99.9% uptime allow?
About 43 minutes a month, or 8 hours 45 minutes a year. The step up to 99.99% cuts that to roughly 4 minutes a month — which is why the extra nine costs considerably more to provide.
Is a 99.9% SLA worth paying extra for?
It depends what an hour offline costs you. For a shop taking orders continuously, the difference between 99% and 99.9% is easily worth it. For a brochure site, it rarely is. Also read what the guarantee actually pays: most SLAs compensate in service credits, not cash, and exclude scheduled maintenance from the calculation.
How do I estimate bandwidth for a new site?
Multiply monthly visits by pages per visit by average page weight, then add substantial headroom. The common error is underestimating page weight — check a real page with browser developer tools rather than guessing, because images and fonts usually dominate and are easy to overlook.
What counts toward bandwidth?
Everything transferred: HTML, images, CSS, JavaScript, fonts, video, API responses and often email traffic. Assets served from a CDN typically do not count against your host after the first fetch, which is one reason a CDN reduces cost as well as latency.
Why is my hosting cost per account higher than expected?
Because the server is usually the smaller part. Control panel licences, backups, monitoring, security tooling and support time are all recurring, and support in particular scales with account count rather than with server capacity. The calculator makes each component explicit so you can see which one dominates.
What is a reasonable overselling ratio?
There is no single safe figure — it depends on how your accounts actually behave. What matters is measuring real usage rather than assuming, and keeping enough headroom that a few accounts growing simultaneously does not degrade everyone. Overselling is normal in shared hosting; overselling without measurement is how a server falls over.