{
    "name": "Error Budget Calculator",
    "url": "https://calculators.geekmidst.com/calculators/error-budget-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/error-budget-calculator.md",
    "category": "Software, cloud & AI",
    "description": "Turn an SLO into an error budget of allowed failed requests, and see how much is used, what is left and the burn rate so far in the window.",
    "summary": "An SLO of 99.9% means 0.1% of events may fail: that is the error budget. Burn rate compares how fast you are spending it with an even pace across the window.",
    "also_called": [
        "SLO calculator",
        "Burn rate 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": "slo",
            "label": "SLO target",
            "type": "number",
            "default": "99.9",
            "unit": "%"
        },
        {
            "name": "total_events",
            "label": "Expected events in the window",
            "type": "number",
            "default": "10000000"
        },
        {
            "name": "bad_events",
            "label": "Failed events so far",
            "type": "number",
            "default": "4000",
            "optional": true
        },
        {
            "name": "window_days",
            "label": "SLO window",
            "type": "number",
            "default": "30",
            "unit": "days"
        },
        {
            "name": "elapsed_days",
            "label": "Days elapsed",
            "type": "number",
            "default": "10",
            "unit": "days",
            "optional": true
        }
    ],
    "outputs": [
        {
            "key": "error_budget",
            "label": "Error budget (failed events allowed)",
            "format": "number"
        },
        {
            "key": "remaining_events",
            "label": "Budget remaining",
            "format": "number"
        },
        {
            "key": "consumed_pct",
            "label": "Budget consumed",
            "format": "percent"
        },
        {
            "key": "burn_rate",
            "label": "Burn rate",
            "format": "multiple"
        },
        {
            "key": "status",
            "label": "Status",
            "format": "text"
        }
    ],
    "formula": {
        "text": "Error budget = (1 − SLO) × Total events;  Consumed = Failed ÷ Budget;  Burn rate = Consumed ÷ (Elapsed ÷ Window)",
        "variables": {
            "SLO": "target success ratio",
            "Burn rate": "1 means the budget runs out exactly at the end of the window"
        }
    },
    "worked_example": {
        "inputs": {
            "slo": "99.9",
            "total_events": "10000000",
            "bad_events": "4000",
            "window_days": "30",
            "elapsed_days": "10"
        },
        "steps": [
            "Budget: 0.001 × 10,000,000 = 10,000 failed events.",
            "Used: 4,000 ÷ 10,000 = 40% after 10 of 30 days (33.3% of the window).",
            "Burn rate: 0.40 ÷ 0.333 = 1.2, so the budget runs out in about 15 more days."
        ],
        "result": "A 99.9% SLO on 10 million events allows 10,000 failures; using 4,000 in the first third of the window is a burn rate of 1.2."
    },
    "interpretation": "A burn rate above 1 means the budget will be gone before the window ends if nothing changes. Many teams alert on short, high burn rates (fast outages) and long, moderate ones (slow leaks), and slow risky releases while the budget is low.",
    "assumptions": [
        "Traffic is spread evenly over the window, so elapsed time is a fair measure of expected events so far."
    ],
    "limitations": [
        "Time-based SLOs (minutes of downtime) use the same idea with minutes instead of events; see the Uptime SLA Calculator."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Where does the idea come from?",
            "answer": "Error budgets and burn-rate alerting are described in Google’s Site Reliability Engineering books."
        },
        {
            "question": "Is burn rate the same as error rate ÷ (1 − SLO)?",
            "answer": "Yes, when traffic is even: the observed error rate divided by the allowed error rate gives the same figure."
        }
    ],
    "sources": [
        {
            "title": "Google Site Reliability Engineering",
            "url": "https://sre.google/"
        }
    ],
    "related": [
        {
            "name": "Uptime SLA Downtime Calculator",
            "url": "https://calculators.geekmidst.com/calculators/website-uptime-sla-downtime-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"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}