{
    "name": "Uptime SLA Downtime Calculator",
    "url": "https://calculators.geekmidst.com/calculators/website-uptime-sla-downtime-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/website-uptime-sla-downtime-calculator.md",
    "category": "Software, cloud & AI",
    "description": "Convert an uptime percentage such as 99.9% or 99.99% into the downtime it allows per day, week, month, quarter or year, in minutes and seconds.",
    "summary": "An uptime target leaves a fixed slice of time for outages: the period length × (1 − uptime). At 99.9%, that is 43 minutes 12 seconds in a 30-day month.",
    "also_called": [
        "SLA calculator",
        "Availability calculator",
        "Nines calculator"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "sla",
            "label": "Uptime target",
            "type": "number",
            "default": "99.9",
            "unit": "%"
        },
        {
            "name": "period",
            "label": "Period",
            "type": "select",
            "default": "month30",
            "options": {
                "day": "Day",
                "week": "Week",
                "month30": "30-day month",
                "month": "Average month (30.44 days)",
                "quarter": "Average quarter (91.31 days)",
                "year365": "365-day year",
                "custom": "Custom number of days"
            }
        },
        {
            "name": "custom_days",
            "label": "Period length",
            "type": "number",
            "default": "28",
            "unit": "days",
            "shown_when": {
                "period": "custom"
            }
        }
    ],
    "outputs": [
        {
            "key": "allowed_downtime_minutes",
            "label": "Allowed downtime",
            "format": "number"
        },
        {
            "key": "allowed_downtime",
            "label": "Allowed downtime",
            "format": "text"
        },
        {
            "key": "allowed_downtime_seconds",
            "label": "In seconds",
            "format": "number"
        },
        {
            "key": "allowed_downtime_hours",
            "label": "In hours",
            "format": "number"
        },
        {
            "key": "period_days",
            "label": "Period length",
            "format": "number"
        }
    ],
    "formula": {
        "text": "Allowed downtime = Period length × (1 − Uptime% ÷ 100)",
        "variables": {
            "Period length": "the measurement window in minutes (30 days = 43,200 min; 365 days = 525,600 min)",
            "Uptime%": "the availability target"
        }
    },
    "worked_example": {
        "inputs": {
            "sla": "99.9",
            "period": "month30",
            "custom_days": "28"
        },
        "steps": [
            "A 30-day month is 30 × 24 × 60 = 43,200 minutes.",
            "Downtime share: 1 − 0.999 = 0.001.",
            "43,200 × 0.001 = 43.2 minutes = 43 min 12 s."
        ],
        "result": "A 99.9% uptime target allows 43 minutes 12 seconds of downtime in a 30-day month (8 h 45 min 36 s a year)."
    },
    "interpretation": "Each extra nine cuts the allowance tenfold: 99.99% leaves about 4.3 minutes a month, which is less than most manual incident responses take. Higher targets need automated failover rather than faster humans.",
    "assumptions": [
        "Downtime is measured as whole-service unavailability over the chosen calendar period."
    ],
    "limitations": [
        "Real SLAs define what counts as downtime (for example, excluding planned maintenance, or measuring in 5-minute intervals); read your contract’s definition."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Which month length should I use?",
            "answer": "Use whatever your SLA uses. Many use a calendar month, so 28 to 31 days; 30 days and the average month (30.44 days) are common approximations."
        },
        {
            "question": "Is availability the same as uptime?",
            "answer": "Usually yes in SLAs. Request-based SLOs instead count the share of successful requests; use the Error Budget Calculator for those."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Error Budget Calculator",
            "url": "https://calculators.geekmidst.com/calculators/error-budget-calculator"
        },
        {
            "name": "P95 Latency Calculator",
            "url": "https://calculators.geekmidst.com/calculators/p95-latency-calculator"
        },
        {
            "name": "Percentage Calculator",
            "url": "https://calculators.geekmidst.com/calculators/percentage-calculator"
        },
        {
            "name": "Availability Percentage Calculator",
            "url": "https://calculators.geekmidst.com/calculators/availability-percentage-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}