{
  "slug": "saas-payback",
  "title": "CAC Payback Period Calculator",
  "heading": "CAC Payback Period Calculator",
  "category": "financial",
  "url": "https://www.revenuelab.fyi/toolbox/saas-payback",
  "summary": "Months to earn back what a customer cost to acquire.",
  "description": "Payback measures how fast the cash comes back, which matters more than LTV when you are funding growth from operations. Under 12 months is efficient; over 24 means you need outside capital to grow.",
  "formula": "Payback = CAC ÷ (ARPU × Gross margin).",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=saas-payback",
  "inputs": [
    {
      "id": "cac",
      "label": "CAC",
      "kind": "number",
      "hint": null,
      "default": 900,
      "unit": "$",
      "min": 0,
      "max": null
    },
    {
      "id": "arpu",
      "label": "Monthly revenue per customer",
      "kind": "number",
      "hint": null,
      "default": 120,
      "unit": "$",
      "min": 0.01,
      "max": null
    },
    {
      "id": "margin",
      "label": "Gross margin",
      "kind": "number",
      "hint": null,
      "default": 80,
      "unit": "%",
      "min": 1,
      "max": 100
    },
    {
      "id": "churn",
      "label": "Monthly churn",
      "kind": "number",
      "hint": null,
      "default": 2.5,
      "unit": "%",
      "min": 0.01,
      "max": 50
    }
  ],
  "outputs": [
    {
      "id": "payback",
      "label": "CAC payback (months)",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "contribution",
      "label": "Monthly contribution per customer",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "lifespan",
      "label": "Expected lifespan (months)",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "profitAfterPayback",
      "label": "Profit after payback",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "verdict",
      "label": "Read",
      "format": "raw",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "CAC: 900 $",
      "Monthly revenue per customer: 120 $",
      "Gross margin: 80 %",
      "Monthly churn: 2.5 %"
    ],
    "outputs": [
      "CAC payback (months): 9.4",
      "Monthly contribution per customer: $96.00",
      "Expected lifespan (months): 40",
      "Profit after payback: $2,940.00",
      "Read: Efficient — pays back inside a year"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter cac ($).",
      "Enter monthly revenue per customer ($).",
      "Enter gross margin (%).",
      "Enter monthly churn (%).",
      "Read your cac payback (months) 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": {
        "cac": 550,
        "arpu": 70,
        "margin": 48,
        "churn": 1.5
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "cac": 900,
        "arpu": 120,
        "margin": 80,
        "churn": 2.5
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "cac": 1450,
        "arpu": 190,
        "margin": 100,
        "churn": 4
      }
    }
  ],
  "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 does the cac payback period calculator work?",
      "a": "Payback measures how fast the cash comes back, which matters more than LTV when you are funding growth from operations. Under 12 months is efficient; over 24 means you need outside capital to grow. The underlying maths is: Payback = CAC ÷ (ARPU × Gross margin)."
    },
    {
      "q": "What do I need to enter?",
      "a": "4 values: cac, monthly revenue per customer, gross margin, and monthly churn. Each field starts with a sensible default, so you can change one number at a time and watch the result move."
    },
    {
      "q": "What does the cac payback (months) result mean?",
      "a": "It is returned as a decimal number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds."
    },
    {
      "q": "Is this calculator free, and do I need an account?",
      "a": "Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser."
    },
    {
      "q": "How accurate is the result?",
      "a": "It applies the standard formula exactly, so the arithmetic is precise. Results are estimates before tax, fees, and inflation unless an input explicitly covers them."
    },
    {
      "q": "Who is this tool for?",
      "a": "It's built for anyone comparing money scenarios before committing — budgeting a payment, sanity-checking a quote, or seeing what a change in rate or term actually costs."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/cac",
    "https://www.revenuelab.fyi/toolbox/ltv",
    "https://www.revenuelab.fyi/toolbox/burn-rate"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — CAC Payback Period Calculator (https://www.revenuelab.fyi/toolbox/saas-payback)"
}