Uptime & Downtime Calculator

99.9% uptime (three nines) allows about 43 minutes of downtime per 30-day month. Broken down by period:

• per day: about 1 minute 26 seconds
• per week: about 10 minutes
• per month: about 43 minutes
• per year: about 8 hours 46 minutes

The math is the length of the period multiplied by 0.1%. Three nines is a common target for standard business services, while revenue-critical systems often aim higher. To see whether you stay within that budget, WebPixie uptime monitoring measures real availability from several regions.

99.99% allows about ten times less downtime than 99.9%, cutting the monthly budget from roughly 43 minutes to about 4 minutes. Each additional nine reduces permitted downtime by an order of magnitude, which is why every step up is harder and usually more expensive. Four nines, at about 4 minutes a month, leaves little room for a slow deploy or a brief network blip, so it generally requires redundancy and automated failover. The calculator above lets you enter each percentage and compare the budgets side by side. You can see what monitoring each WebPixie plan includes on the pricing page.

A good target depends on the service, but 99.9% is a widely used baseline for business sites and applications. Typical tiers:

• 99% to 99.5% for internal tools
• 99.9% for most business services
• 99.95% to 99.99% for ecommerce, payment, and revenue-critical systems

Higher is not always better, because each extra nine demands more redundancy and faster detection for a smaller reduction in downtime. Pick the lowest target that meets user expectations, express it as a downtime budget above, then track it. WebPixie uptime monitoring records real availability so you can confirm the target is realistic.

An SLA (service level agreement) is a formal commitment to a minimum availability, usually written as an uptime percentage such as 99.95%. The allowed downtime is the error budget the SLA permits before it is breached; a 99.95% SLA, for example, allows about 22 minutes per month. Teams use the budget to decide how much risk a release or maintenance window can take. The calculator above converts any SLA figure into plain minutes for the day, week, month, and year. To prove you met an SLA you need a record of real availability, which WebPixie uptime monitoring and incident management provide.

It depends on the SLA, and the distinction matters. Many SLAs exclude scheduled maintenance announced in advance, counting only unplanned outages, while others count all unavailability. When you set a target, decide which definition you use, because excluding maintenance makes a given percentage easier to meet. The calculator above treats the period as continuous 24/7 time, so the downtime it shows is the total budget before any exclusions you apply. If your SLA excludes maintenance, subtract those windows from the measured downtime. WebPixie uptime monitoring calculates availability with the industry-standard method that excludes unmonitored periods.

Estimate the cost of downtime by multiplying the expected downtime by your revenue or cost per hour. If your site earns $2,000 an hour and your target allows 4 hours of downtime a year, the modeled exposure is about $8,000. The calculator above includes a cost mode where you enter an hourly figure and see the projected loss for each period, which helps justify spending on redundancy or faster recovery. The estimate is only as good as the hourly figure, so use a realistic blended number that includes lost sales and recovery effort. Pairing the estimate with uptime monitoring gives you both the budget and the live measurement.

Five nines means 99.999% availability, which allows only about 26 seconds of downtime per month, or roughly 5 minutes 15 seconds per year. It is the standard often quoted for telecom and critical infrastructure. Reaching it is demanding because almost no manual response is fast enough, so it requires redundant systems, automated failover, and detection within seconds. For most websites five nines is more than the business needs, and the cost outweighs the benefit. The nines table in the calculator above lists five nines next to the lower tiers so you can compare the budgets directly. Fast detection through uptime monitoring is a prerequisite for any high tier.

Uptime percentage is available time divided by total time, times 100, but how you measure the available time matters. Monitoring tools check a site at a fixed interval from one or more locations, record each check as up or down, then add up the down periods. A shorter interval and several locations give a more accurate figure and catch regional outages. The calculator above also has a reverse mode: enter an observed outage and it returns the resulting percentage, which is handy after an incident. WebPixie uptime monitoring checks from several regions and retries before counting a failure, so a single failed check does not distort the percentage.