{
  "id": "coast-fire",
  "version": "01562a886d68",
  "status": "published",
  "name": "Coast FIRE Calculator",
  "question": "Have I saved enough for Coast FIRE?",
  "summary": "Computes your Coast FIRE number: what you need invested today to reach your FIRE number by your retirement age with no more saving, and when you get there.",
  "category": "finance",
  "subcategory": "retirement",
  "url": "https://www.acalculator.org/finance/coast-fire-calculator",
  "markdown": "https://www.acalculator.org/finance/coast-fire-calculator.md",
  "kind": "schedule",
  "method": "Coast FIRE number = (yearly spending ÷ withdrawal rate) ÷ (1 + real return)^(retirement age − age), with real return = (1 + R) ÷ (1 + inflation) − 1; each month the balance grows at the monthly real rate plus your saving until it reaches that month’s Coast FIRE number.",
  "assumptions": [
    "All amounts are in today’s money: your saving and spending rise with prices.",
    "The return and inflation stay the same every year. Real returns go up and down.",
    "You stop saving once you reach Coast FIRE, and add nothing more until retirement.",
    "The withdrawal rate is a rule of thumb from past market returns, not a guarantee.",
    "Taxes, fees, and Social Security are not included.",
    "This is an estimate for planning, not financial advice."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "age": {
        "title": "Your age",
        "description": "Your age now.",
        "type": "integer",
        "minimum": 18,
        "maximum": 79
      },
      "retire": {
        "title": "Retirement age",
        "description": "The age you want to retire and start spending your investments.",
        "type": "integer",
        "minimum": 19,
        "maximum": 100
      },
      "spending": {
        "title": "Yearly spending in retirement",
        "description": "What you expect to spend each year once you retire, in today’s money.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 1,
        "maximum": 100000000
      },
      "saved": {
        "title": "Invested today",
        "description": "What you have invested for retirement now.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 0,
        "maximum": 1000000000
      },
      "monthly": {
        "title": "You save each month until you coast",
        "description": "What you invest each month, in today’s money, until you reach Coast FIRE. Then you stop.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 0,
        "maximum": 10000000
      },
      "rate": {
        "title": "Expected yearly return",
        "description": "The yearly return before inflation. It stays the same every year.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 0,
        "maximum": 20
      },
      "inflation": {
        "title": "Prices rise each year by",
        "description": "The yearly inflation rate. The real return is (1 + return) ÷ (1 + inflation) − 1.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 0,
        "maximum": 20
      },
      "swr": {
        "title": "Safe withdrawal rate",
        "description": "The share of your savings you plan to spend in the first year of retirement, often 4%.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 1,
        "maximum": 10
      }
    }
  },
  "outputs": {
    "coast": {
      "label": "Your Coast FIRE number today",
      "description": "FIRE number ÷ (1 + real return)^(years to retirement), in today’s money.",
      "format": "money"
    },
    "fire": {
      "label": "Your FIRE number",
      "description": "Yearly spending ÷ safe withdrawal rate, in today’s money.",
      "format": "money"
    },
    "gap": {
      "label": "Still needed today",
      "description": "The Coast FIRE number minus what you have invested, or 0 if you are there.",
      "format": "money"
    },
    "coastAge": {
      "label": "You can coast from age",
      "description": "Your age when your investments first reach the Coast FIRE number, saving each month until then.",
      "format": "number"
    },
    "atRetire": {
      "label": "Invested at retirement",
      "description": "Your investments at your retirement age, in today’s money.",
      "format": "money"
    },
    "status": {
      "label": "Coast FIRE before retirement?",
      "description": "Shown when your investments do not reach the Coast FIRE number before your retirement age.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "age": 30,
      "retire": 65,
      "spending": 50000,
      "saved": 100000,
      "monthly": 1500,
      "rate": 7,
      "inflation": 3,
      "swr": 4
    },
    "outputs": {
      "coast": 329443.28416663595,
      "fire": 1250000,
      "gap": 229443.28416663595,
      "coastAge": 47.5,
      "atRetire": 1250357.0585440148
    },
    "text": "To coast to $1,250,000.00 by age 65, you need $329,443.28 invested today; you have $100,000.00, so you still need $229,443.28."
  },
  "examples": [
    {
      "given": {
        "age": 30,
        "retire": 65,
        "spending": 40000,
        "saved": 50000,
        "rate": 7,
        "inflation": 0,
        "swr": 4
      },
      "expect": {
        "fire": 1000000,
        "coast": 93662.93896983446,
        "gap": 43662.93896983446
      },
      "source": "hand calculation in content.mdx: 1,000,000 ÷ 1.07^35"
    },
    {
      "given": {
        "age": 30,
        "retire": 65,
        "spending": 60000,
        "saved": 100000,
        "monthly": 500,
        "rate": 7,
        "inflation": 3,
        "swr": 4
      },
      "expect": {
        "fire": 1500000,
        "coast": 395331.94099996303
      },
      "source": "hand calculation in content.mdx: 1,500,000 × (1.03 ÷ 1.07)^35"
    },
    {
      "given": {
        "age": 30,
        "retire": 80,
        "spending": 24000,
        "saved": 50000,
        "monthly": 1000,
        "rate": 3,
        "inflation": 3,
        "swr": 4
      },
      "expect": {
        "fire": 600000,
        "coast": 600000,
        "coastAge": 75.83333333333334
      },
      "source": "hand calculation in content.mdx: at a 0% real return, (600,000 − 50,000) ÷ 1,000 = 550 months"
    },
    {
      "given": {
        "age": 40,
        "retire": 60,
        "spending": 40000,
        "saved": 500000,
        "rate": 7,
        "inflation": 2,
        "swr": 4
      },
      "expect": {
        "gap": 0,
        "coastAge": 40
      },
      "source": "hand calculation in content.mdx: $500,000 is above the Coast FIRE number, so you coast now"
    }
  ],
  "sources": [
    "W. P. Bengen, \"Determining Withdrawal Rates Using Historical Data\", Journal of Financial Planning, October 1994.",
    "P. L. Cooley, C. M. Hubbard, D. T. Walz, \"Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable\", AAII Journal, February 1998.",
    "Present value and the real rate of return: S. A. Broverman, Mathematics of Investment and Credit, chapter 1.",
    "U.S. Securities and Exchange Commission, Investor.gov compound interest calculator and formula. https://www.investor.gov/financial-tools-calculators/calculators/compound-interest-calculator"
  ],
  "related": [
    "fire",
    "401k",
    "investment"
  ],
  "changelog": []
}