{
  "slug": "emergency-fund-vs-debt-payoff-calculator",
  "title": "Emergency Fund vs Debt Payoff Calculator",
  "heading": "Emergency Fund vs Debt Payoff Calculator",
  "category": "financial",
  "url": "https://www.revenuelab.fyi/toolbox/emergency-fund-vs-debt-payoff-calculator",
  "summary": "Split spare cash between savings and debt without guessing.",
  "description": "Paying high-rate debt beats almost any guaranteed return, which argues for throwing everything at the balance — until an unexpected car repair puts the whole amount straight back on the card at the same rate. The practical answer is a sequence: a small starter cushion, then aggressive payoff, then a full emergency fund. This calculator models a split of your monthly surplus, showing payoff date and interest cost at each allocation, how many months of expenses you would have banked, and the interest cost of holding that cushion. Use it to find the smallest cushion you can live with rather than the theoretically optimal one.",
  "formula": "Debt is amortized at the chosen split; the savings side accrues at the savings APY. Cushion cost = extra interest from the slower payoff.",
  "dateModified": "2026-09-06",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=emergency-fund-vs-debt-payoff-calculator",
  "inputs": [
    {
      "id": "balance",
      "label": "High-rate debt balance",
      "kind": "number",
      "hint": null,
      "default": 8500,
      "unit": "$",
      "min": 0,
      "max": 500000
    },
    {
      "id": "apr",
      "label": "Debt APR",
      "kind": "number",
      "hint": null,
      "default": 22.9,
      "unit": "%",
      "min": 0,
      "max": 40
    },
    {
      "id": "surplus",
      "label": "Monthly surplus available",
      "kind": "number",
      "hint": null,
      "default": 600,
      "unit": "$",
      "min": 0,
      "max": 50000
    },
    {
      "id": "toSavings",
      "label": "Share sent to savings",
      "kind": "number",
      "hint": null,
      "default": 30,
      "unit": "%",
      "min": 0,
      "max": 100
    },
    {
      "id": "expenses",
      "label": "Essential monthly expenses",
      "kind": "number",
      "hint": null,
      "default": 3400,
      "unit": "$",
      "min": 1,
      "max": 100000
    },
    {
      "id": "apy",
      "label": "Savings APY",
      "kind": "number",
      "hint": null,
      "default": 4,
      "unit": "%",
      "min": 0,
      "max": 10
    },
    {
      "id": "startingCash",
      "label": "Cash already saved",
      "kind": "number",
      "hint": null,
      "default": 500,
      "unit": "$",
      "min": 0,
      "max": 500000
    }
  ],
  "outputs": [
    {
      "id": "cushionCost",
      "label": "Extra interest cost of saving alongside",
      "format": "currency",
      "hint": null,
      "primary": true
    },
    {
      "id": "savedAtPayoff",
      "label": "Cash saved by payoff date",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "monthsCovered",
      "label": "Months of expenses covered",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "payoffMonths",
      "label": "Payoff with the split",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "focusedMonths",
      "label": "Payoff if all surplus goes to debt",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "splitInterest",
      "label": "Total interest with the split",
      "format": "currency",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "High-rate debt balance: 8500 $",
      "Debt APR: 22.9 %",
      "Monthly surplus available: 600 $",
      "Share sent to savings: 30 %",
      "Essential monthly expenses: 3400 $",
      "Savings APY: 4 %",
      "Cash already saved: 500 $"
    ],
    "outputs": [
      "Extra interest cost of saving alongside: $720",
      "Cash saved by payoff date: $5,425",
      "Months of expenses covered: 1.6",
      "Payoff with the split: 26",
      "Payoff if all surplus goes to debt: 17",
      "Total interest with the split: $2,420"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter high-rate debt balance ($).",
      "Enter debt apr (%).",
      "Enter monthly surplus available ($).",
      "Enter share sent to savings (%).",
      "Enter essential monthly expenses ($).",
      "Enter savings apy (%).",
      "Enter cash already saved ($).",
      "Read your extra interest cost of saving alongside on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "balance": 5100,
        "apr": 22.9,
        "surplus": 350,
        "toSavings": 20,
        "expenses": 2000,
        "apy": 2.4,
        "startingCash": 300
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "balance": 8500,
        "apr": 22.9,
        "surplus": 600,
        "toSavings": 30,
        "expenses": 3400,
        "apy": 4,
        "startingCash": 500
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "balance": 13600,
        "apr": 22.9,
        "surplus": 950,
        "toSavings": 50,
        "expenses": 5400,
        "apy": 6.4,
        "startingCash": 800
      }
    }
  ],
  "limitations": [
    "Results are estimates before tax, fees, and inflation unless an input explicitly covers them.",
    "Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.",
    "This is educational maths, not financial advice. Check anything contractual with the lender or your accountant."
  ],
  "faq": [
    {
      "q": "How big should the starter cushion be?",
      "a": "A common rule is one month of essentials or around $1,000–$2,000 before attacking high-rate debt, then rebuilding to three to six months afterwards."
    },
    {
      "q": "Why not save everything first?",
      "a": "Because a 23% APR balance grows faster than any savings account pays. The cushion buys insurance against re-borrowing, not returns."
    },
    {
      "q": "Does a 0% card change the answer?",
      "a": "Yes. If the debt costs nothing during a promo window, saving is cheaper — but plan for the balance that remains when the promo ends."
    },
    {
      "q": "Should retirement matching come first?",
      "a": "Usually yes. An employer match is an immediate return that typically beats even high-rate debt payoff on the matched portion."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/credit-card-payoff-time-calculator",
    "https://www.revenuelab.fyi/toolbox/debt-avalanche-vs-snowball-calculator"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Emergency Fund vs Debt Payoff Calculator (https://www.revenuelab.fyi/toolbox/emergency-fund-vs-debt-payoff-calculator)"
}