{
  "slug": "401k-growth",
  "title": "401(k) Growth Calculator",
  "heading": "401(k) Growth Calculator",
  "category": "financial",
  "url": "https://www.revenuelab.fyi/toolbox/401k-growth",
  "summary": "Project your balance with contributions and employer match.",
  "description": "Your 401(k) grows from three sources: what you put in, what your employer matches, and compounding. The match is the part people leave on the table.",
  "formula": "FV = balance × (1+r)^n + annual contributions compounded",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=401k-growth",
  "inputs": [
    {
      "id": "balance",
      "label": "Current balance",
      "kind": "number",
      "hint": null,
      "default": 40000,
      "unit": "$",
      "min": 0,
      "max": null
    },
    {
      "id": "salary",
      "label": "Annual salary",
      "kind": "number",
      "hint": null,
      "default": 90000,
      "unit": "$",
      "min": 0,
      "max": null
    },
    {
      "id": "pct",
      "label": "Your contribution",
      "kind": "number",
      "hint": null,
      "default": 10,
      "unit": "% of salary",
      "min": 0,
      "max": 100
    },
    {
      "id": "match",
      "label": "Employer match",
      "kind": "number",
      "hint": null,
      "default": 4,
      "unit": "% of salary",
      "min": 0,
      "max": 25
    },
    {
      "id": "years",
      "label": "Years to retirement",
      "kind": "number",
      "hint": null,
      "default": 25,
      "unit": null,
      "min": 1,
      "max": 60
    },
    {
      "id": "rate",
      "label": "Annual return",
      "kind": "number",
      "hint": null,
      "default": 7,
      "unit": "%",
      "min": 0,
      "max": 20
    }
  ],
  "outputs": [
    {
      "id": "total",
      "label": "Balance at retirement",
      "format": "currency",
      "hint": null,
      "primary": true
    },
    {
      "id": "contributed",
      "label": "Total contributed",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "growth",
      "label": "Investment growth",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "employerTotal",
      "label": "Employer match total",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "monthly",
      "label": "Monthly contribution",
      "format": "currency",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Current balance: 40000 $",
      "Annual salary: 90000 $",
      "Your contribution: 10 % of salary",
      "Employer match: 4 % of salary",
      "Years to retirement: 25",
      "Annual return: 7 %"
    ],
    "outputs": [
      "Balance at retirement: $1,014,035",
      "Total contributed: $355,000",
      "Investment growth: $659,035",
      "Employer match total: $90,000",
      "Monthly contribution: $1,050"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter current balance ($).",
      "Enter annual salary ($).",
      "Enter your contribution (% of salary).",
      "Enter employer match (% of salary).",
      "Enter years to retirement.",
      "Enter annual return (%).",
      "Read your balance at retirement 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": 24000,
        "salary": 54000,
        "pct": 6,
        "match": 2.4,
        "years": 15,
        "rate": 7
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "balance": 40000,
        "salary": 90000,
        "pct": 10,
        "match": 4,
        "years": 25,
        "rate": 7
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "balance": 64000,
        "salary": 144000,
        "pct": 16,
        "match": 6.4,
        "years": 40,
        "rate": 7
      }
    }
  ],
  "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 401(k) growth calculator work?",
      "a": "Your 401(k) grows from three sources: what you put in, what your employer matches, and compounding. The match is the part people leave on the table. The underlying maths is: FV = balance × (1+r)^n + annual contributions compounded"
    },
    {
      "q": "What do I need to enter?",
      "a": "6 values: current balance, annual salary, your contribution, employer match, years to retirement, and annual return. 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 balance at retirement result mean?",
      "a": "It is returned as a money amount in US dollars 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/retirement-savings",
    "https://www.revenuelab.fyi/toolbox/roth-vs-traditional"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — 401(k) Growth Calculator (https://www.revenuelab.fyi/toolbox/401k-growth)"
}