Website Downtime Cost & Revenue Risk Calculator
See what one hour of downtime costs your business, how much downtime your host’s uptime guarantee still allows, and how little the SLA credit pays back.
Every hosting plan advertises an uptime guarantee: 99.9%, 99.99%, “enterprise-grade reliability”. Turned around, that percentage is an amount of downtime your host is allowed before it breaks its promise. This calculator converts your SLA into hours, works out what an hour of downtime costs you in lost revenue and staff time, prices a single outage including the cost of fixing it, and compares that with the SLA credit you would get back. Every formula is shown in the results and below the calculator.
Only revenue is required. Other defaults are examples; change them to match your business.
Writing about hosting SLAs, uptime or the cost of downtime? Copy a link, or embed the working calculator on your own page. Every result also has its own shareable link.
PaidHosting.com. (2026). Website Downtime Cost & Revenue Risk Calculator. Retrieved from https://www.paidhosting.com/downtime-cost-calculator/
Uptime guarantees in hours and minutes
How much downtime each common uptime guarantee allows, worked out for a 365-day year (8,760 hours), an average month (730 hours), a week and a day. Free to reuse with a link to this page.
| Uptime guarantee | Per year | Per month | Per week | Per day |
|---|---|---|---|---|
| 99% (“two nines”) | 3d 15h 36m | 7h 18m | 1h 41m | 14m |
| 99.5% | 1d 19h 48m | 3h 39m | 50m | 7m |
| 99.9% (“three nines”) | 8h 46m | 44m | 10m | 1m |
| 99.95% | 4h 23m | 22m | 5m | 43s |
| 99.99% (“four nines”) | 53m | 4m | 1m | 9s |
| 99.999% (“five nines”) | 5m | 26s | 6s | 1s |
Each extra “nine” cuts allowed downtime by a factor of ten. Most SLAs measure uptime month by month, so the monthly column is usually the one that decides whether you are owed a credit.
How this calculator works
The yearly exposure assumes outages fall at average times; the single-outage estimate lets you choose a busier or quieter time. Fixing costs are counted per outage, not in the yearly figure, because the number of incidents varies.
Going from 99% to 99.9% cuts allowed downtime from 3 days 15 hours to 8 hours 46 minutes a year. Going from 99.9% to 99.99% cuts it to 53 minutes. The results show what each step is worth to you in dollars a month.
An outage during a sale or launch costs more than one in the middle of the night. Use the “When it happens” setting to price a single outage at a quiet, average, busy or peak time.
When a host misses its SLA, the usual remedy is a credit worth a percentage of your hosting bill, not your lost revenue. The results put the two side by side so you can see the gap.
Example results
Worked examples using the calculator’s formulas. The businesses are illustrative, not survey data. Click a row to load it and change the numbers.
| Example | Cost per hour down | Allowed downtime / year | Yearly exposure | |
|---|---|---|---|---|
| Small online store $15,000 a month, all online, no staff affected, 99.9% SLA | $20.55 | 8h 46m | $180 | Open in calculator |
| Ad-supported content site $4,000 a month, 99% SLA on a budget plan | $5.48 | 3d 15h 36m | $480 | Open in calculator |
| Growing ecommerce brand $150,000 a month, 5 staff at $30/hour who can’t work, 99.9% SLA | $355 | 8h 46m | $3,114 | Open in calculator |
| SaaS business $500,000 a month, 20% of lost sign-ups recovered later, 20 staff at $45/hour, 99.95% SLA | $1,448 | 4h 23m | $6,342 | Open in calculator |
How your number compares with published research
Published downtime-cost studies mostly survey large companies, so their figures are far higher than most small sites will see. They are useful context, not a substitute for your own number.
- ITIC, 2024 Hourly Cost of Downtime survey: for over 90% of mid-size and large enterprises, one hour of downtime costs more than $300,000; for 41% of enterprises it costs $1 million to over $5 million.
- New Relic, Observability Forecast 2025: the median cost of a high-impact IT outage is $2 million an hour; for retail and ecommerce the median is $1 million an hour.
- Splunk, The Hidden Costs of Downtime 2026: Global 2000 companies lose an average of $300 million a year to unplanned downtime.
- Uptime Institute, Annual Outage Analysis 2026: 1 in 5 data center operators said their most recent major outage cost more than $1 million.
- Small businesses: we could not find a current, primary-source downtime-cost figure for small businesses, which is why this calculator uses your own revenue.
More figures, trends and sources: website downtime cost statistics.
Reading your results
What one hour of downtime costs you in lost revenue and staff time, whoever is at fault. This is the number worth remembering.
The most downtime your SLA permits, and what it would cost if all of it were used. It is a ceiling, not a prediction: your real downtime can be lower or higher.
The cost of a single outage of the length and timing you chose, including fixing it, next to the SLA credit you would receive. A credit is usually only owed if the outage takes your host below its guarantee for that month.
How much a higher uptime guarantee is worth to you each month. If a more reliable plan costs less extra than this, it pays for itself on paper, provided the host actually delivers it.
Frequently Asked Questions
It depends on your business, so there is no single figure that fits everyone. For a site that earns money online, start with your monthly website revenue divided by the 730 hours in an average month: $15,000 a month is about $20.55 an hour, and $500,000 a month is about $685 an hour. Add the hourly cost of staff who can’t work while the site is down, and the cost of fixing the problem. The calculator above does this for you.
Over a 365-day year, 99% allows 3 days 15 hours 36 minutes of downtime, 99.9% allows 8 hours 46 minutes, 99.95% allows 4 hours 23 minutes, 99.99% allows 53 minutes, and 99.999% allows about 5 minutes. Most SLAs measure uptime per month, so divide by 12: 99.9% allows about 44 minutes a month.
Usually as a service credit against a future hosting bill, calculated as a percentage of what you pay for hosting, not of the revenue you lost. Check your host’s SLA for the credit amount, how to claim it (many require you to ask within a set time), and wording such as “sole remedy”, which means the credit is all you can claim. The calculator compares that credit with the cost of an outage.
For many small business and content sites it is a reasonable baseline: about 44 minutes a month, or 8 hours 46 minutes a year. If an hour of downtime costs you a lot, use the chart in the results. It shows how much moving to the next guarantee is worth to you each month, so you can compare that with the extra cost of a more reliable plan.
Use an independent uptime monitoring service, which checks your site every few minutes from outside your host’s network and records the result. Some offer free plans for a small number of sites. Let it run for at least a month before relying on the figure, and enter it in the “measured uptime” field to compare it with your host’s promise.
Your customers can’t use the site either way, but many SLAs exclude scheduled maintenance from the uptime calculation as long as the host gives notice. So a host can meet its SLA while your site is unavailable during announced maintenance. Check how your host’s SLA defines downtime.
Not every sale is lost for good. Some customers come back and buy after the site is back up. If you know that a share of buyers return, enter it so the calculator only counts the revenue that is really lost. If you are not sure, leave it at 0% for a cautious estimate.
Set up independent uptime monitoring with instant alerts, keep tested off-site backups you can restore quickly, write a simple incident plan, and use a status page to keep customers informed. These reduce the impact of an outage. If your yearly exposure is high, infrastructure such as load balancing, failover or multi-region hosting is what prevents the outage in the first place.
An uptime guarantee
is a promise on paper.
The percentage on a hosting pricing page tells you what a company is willing to commit to, backed by a credit worth a fraction of what an outage might cost you. It doesn’t tell you how reliable that host has been, or what an hour of downtime is worth to your business.
Know your real number before an outage
puts it in front of your customers.