This SLA calculator and uptime to downtime converter updates instantly as you work. Start with the SLA target, counting mode, and maintenance settings, then use the compliance check for the actual downtime experienced.

• Choose an SLA target using a preset, the slider, or the custom percentage field.
• Select 24/7 operation for always-on services, or business hours only when the SLA applies to an 8-hour day, five days per week.
• Add a monthly planned-maintenance window if your SLA excludes scheduled work.
• Read the allowed downtime per day, week, 30-day month, and year from the results table, and use Copy to capture that table for records or estimates.
• In SLA Compliance Check, enter the agreed SLA target and the actual downtime in hours, minutes, or seconds. The Calculate button stays gray until a downtime greater than zero is entered.
• Click Calculate to see whether the SLA passed (green) or failed (red), the achieved uptime, and by how much the allowance was met or exceeded. The line under the result states the counting mode and maintenance window used.
• Use Copy or CSV under the result to export the full compliance report for tickets or SLA claims, and Clear all to reset the calculator.
• After the result appears, optional buttons offer a three-, four-, and five-nines comparison, a “nines” quick-reference chart, and a service-credit estimator with fixed or tiered credit models.

99.9 uptime meaning: what three nines actually allow

The 99.9 uptime meaning in practical terms: out of every 1,000 minutes of service, up to 1 minute may be unavailable. Over a 30-day month that is 43 minutes 12 seconds; over a year, 8 hours 45 minutes 36 seconds. It is the most common baseline for business SaaS and hosting contracts.

99.99 downtime per month: four nines

The 99.99 downtime per month allowance is roughly 4 minutes 19 seconds per 30-day month, or about 52 minutes 34 seconds per year. Reaching four nines usually requires redundant infrastructure and automated failover, because a single one-hour outage would blow the entire annual budget.

How much downtime is 99.999: five nines?

How much downtime is 99.999 in practice? About 5 minutes 15 seconds per year, less than a coffee break, and just 26 seconds per month. Five nines is the traditional carrier-grade telecom benchmark and demands fully redundant, geographically diverse systems.

Formulas used

Allowed downtime = eligible seconds × (1 − SLA % ÷ 100). Eligible seconds = total period seconds − prorated maintenance. Standard periods: day = 24 h, week = 7 days, month = 30 days, year = 365 days. Business-hours mode assumes 8 h/day and 5 days/week, derived from 22 business days per month and 260 business days per year. Achieved uptime = (1 − observed downtime ÷ eligible time) × 100.

Service credit = monthly fee × credit % ÷ 100, applied per affected billing month. Fixed Based uses one set percentage; Tiered Approach picks the percentage by how far the achieved uptime fell below the target (for example 10% just below target, 25% further below, 50% well below).

The calculator converts the SLA percentage into a downtime budget by multiplying eligible period time by the downtime fraction: 100% − SLA percentage. Standard 24/7 periods are 24 hours per day, 7 days per week, 30 days per month, and 365 days per year.

In business-hours mode, a day is 8 hours and a week is 5 days. Month and year budgets use the common planning assumptions of 22 business days per month and 260 business days per year.

A maintenance window entered in hours per month is prorated to each reporting period and subtracted before the SLA math. In the compliance check, click Calculate to compare the entered downtime with the allowed downtime for the agreed SLA target and selected period. If the downtime is within the allowance, the result is green; otherwise, it is red. The result, including achieved uptime, can be copied or downloaded as a CSV for records and SLA claims, and Clear all resets every field.

The numbered buttons provide optional follow-up tools: a three-, four-, and five-nines comparison, a standard “nines” reference chart, and a service-credit estimator. The estimator offers two contract models: Fixed Based, a flat percentage of the monthly fee per missed month, and Tiered Approach, which scales the credit by how far the achieved uptime fell below the target. All calculations happen locally in the browser; no data is sent anywhere.