{
  "$comment": "Machine-readable companion to https://valem.run/calculators/tools/fire-planner. Formula, inputs, outputs, engine-verified test vectors, cited sources and the re-runnable Valem ModelSpec behind the page.",
  "url": "https://valem.run/calculators/tools/fire-planner",
  "dataUrl": "https://valem.run/calculators/tools/fire-planner.json",
  "license": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "Decision tools retirement and fire planner model by Valem (https://valem.run/calculators/tools/fire-planner), CC BY 4.0.",
    "note": "Covers the model — the expression of each rule and the arrangement of the catalog. The rates and thresholds themselves are law and are not licensed by anyone; the cited sources are where they come from."
  },
  "verificationUrl": "https://valem.run/calculators/tools/fire-planner/verify",
  "country": "tools",
  "countryName": "Decision tools",
  "formula": "fire-planner",
  "formulaName": "Retirement and FIRE planner",
  "title": "FIRE Calculator — when you can retire",
  "answer": "You are financially independent once your portfolio reaches your annual retirement spending divided by your withdrawal rate — 25 times your spending at the 4% rule — and the age you get there is driven far more by your savings rate than by your investment return.",
  "lang": "en",
  "currency": "USD",
  "taxYear": "",
  "verification": {
    "claim": "internal-consistency",
    "statement": "The Valem engine reproduces this model's stated formula through 4 self-test cases (below, and re-runnable against the spec). That asserts internal consistency, NOT that the formula matches current law — the cited sources are the evidence for that, and carry the date each was last checked.",
    "selfTestCases": 4,
    "ratesAreIllustrative": false,
    "sourcesCheckedOn": "2026-08-02"
  },
  "sources": [],
  "terminalOutput": "sustainableWithdrawal",
  "inputs": [
    {
      "name": "currentAge",
      "type": "integer",
      "label": "Your age",
      "minimum": 16,
      "maximum": 80
    },
    {
      "name": "currentPortfolio",
      "type": "number",
      "label": "Invested today",
      "minimum": 0
    },
    {
      "name": "annualIncome",
      "type": "number",
      "label": "Take-home income / yr",
      "minimum": 0
    },
    {
      "name": "annualSpending",
      "type": "number",
      "label": "Spending / yr",
      "minimum": 0
    },
    {
      "name": "retirementSpending",
      "type": "number",
      "label": "Retirement spending / yr (today's money)",
      "minimum": 0
    },
    {
      "name": "nominalReturnPct",
      "type": "number",
      "label": "Nominal return per year (%)",
      "minimum": 0,
      "maximum": 20
    },
    {
      "name": "inflationPct",
      "type": "number",
      "label": "Inflation per year (%)",
      "minimum": 0,
      "maximum": 20
    },
    {
      "name": "swrPct",
      "type": "number",
      "label": "Safe withdrawal rate (%)",
      "minimum": 0.5,
      "maximum": 10
    },
    {
      "name": "pensionAnnual",
      "type": "number",
      "label": "State or workplace pension / yr",
      "minimum": 0
    },
    {
      "name": "targetRetirementAge",
      "type": "integer",
      "label": "Target retirement age (for Coast FI)",
      "minimum": 30,
      "maximum": 90
    },
    {
      "name": "horizonYears",
      "type": "integer",
      "label": "Project this many years",
      "minimum": 1,
      "maximum": 60
    }
  ],
  "outputs": [
    {
      "name": "annualContribution",
      "type": "number",
      "label": "Saved per year",
      "format": "number",
      "formula": "$round(annualIncome - annualSpending, 2)"
    },
    {
      "name": "savingsRatePct",
      "type": "number",
      "label": "Savings rate",
      "format": "number",
      "formula": "annualIncome <= 0 ? 0 : $round((annualIncome - annualSpending) / annualIncome * 100, 1)"
    },
    {
      "name": "realReturnPct",
      "type": "number",
      "label": "Real return",
      "format": "number",
      "formula": "$round(((1 + nominalReturnPct / 100) / (1 + inflationPct / 100) - 1) * 100, 4)"
    },
    {
      "name": "fiNumber",
      "type": "number",
      "label": "The number you need",
      "format": "number",
      "formula": "$max([0, $round((retirementSpending - pensionAnnual) / (swrPct / 100), 2)])"
    },
    {
      "name": "coastNumber",
      "type": "number",
      "label": "Coast FI number",
      "format": "number",
      "formula": "( $n := targetRetirementAge - currentAge; $n <= 0 ? fiNumber : $round(fiNumber / $power(1 + realReturnPct / 100, $n), 2) )"
    },
    {
      "name": "projection",
      "type": "array",
      "label": "Portfolio against the number you need (today's money)",
      "formula": "$map([0..horizonYears], function($y) { { \"year\": $y, \"age\": currentAge + $y, \"contributed\": $round(currentPortfolio + annualContribution * $y, 2), \"portfolio\": $round($grow(currentPortfolio, annualContribution, realReturnPct / 100, $y), 2), \"target\": fiNumber } })"
    },
    {
      "name": "fiAge",
      "type": "integer",
      "label": "Financially independent at",
      "format": "number",
      "formula": "( $hits := $map(projection, function($p) { $p.portfolio >= $p.target ? $p.age : 0 })[$ > 0]; $count($hits) = 0 ? 0 : $min($hits) )"
    },
    {
      "name": "yearsToFi",
      "type": "integer",
      "label": "Years to get there",
      "format": "number",
      "formula": "fiAge > 0 ? fiAge - currentAge : 0"
    },
    {
      "name": "fiReached",
      "type": "boolean",
      "formula": "fiAge > 0"
    },
    {
      "name": "finalPortfolio",
      "type": "number",
      "formula": "( $p := $map(projection, function($r) { $r.portfolio }); $i := $count($p) - 1; $p[$i] )"
    },
    {
      "name": "sustainableWithdrawal",
      "type": "number",
      "label": "Income at the end",
      "format": "number",
      "formula": "$round(finalPortfolio * swrPct / 100, 2)"
    }
  ],
  "testCases": [
    {
      "description": "age 30 with 100k invested, saving 40k of 100k, 7% nominal against 3% inflation, 4% withdrawal rate",
      "given": {
        "currentAge": 30,
        "currentPortfolio": 100000,
        "annualIncome": 100000,
        "annualSpending": 60000,
        "retirementSpending": 60000,
        "nominalReturnPct": 7,
        "inflationPct": 3,
        "swrPct": 4
      },
      "expect": {
        "annualContribution": 40000,
        "savingsRatePct": 40,
        "realReturnPct": 3.8835,
        "fiNumber": 1500000,
        "coastNumber": 478293.04,
        "projection[0].portfolio": 100000,
        "projection[1].portfolio": 143883.5,
        "projection[22].portfolio": 1582779.59,
        "fiAge": 52,
        "yearsToFi": 22,
        "fiReached": true,
        "finalPortfolio": 4157295.48,
        "sustainableWithdrawal": 166291.82
      }
    },
    {
      "description": "saving 60% instead of 40% brings independence forward five years",
      "given": {
        "annualSpending": 40000
      },
      "expect": {
        "annualContribution": 60000,
        "savingsRatePct": 60,
        "fiNumber": 1500000,
        "fiAge": 47,
        "yearsToFi": 17
      }
    },
    {
      "description": "a 12,000 pension cuts the number you need by exactly the pension capitalised at the withdrawal rate",
      "given": {
        "pensionAnnual": 12000
      },
      "expect": {
        "fiNumber": 1200000,
        "coastNumber": 382634.43,
        "fiAge": 48,
        "yearsToFi": 18
      }
    },
    {
      "description": "spending everything you earn — the pot still compounds, but never reaches the target in the horizon",
      "given": {
        "annualSpending": 100000
      },
      "expect": {
        "annualContribution": 0,
        "savingsRatePct": 0,
        "fiAge": 0,
        "fiReached": false,
        "yearsToFi": 0,
        "finalPortfolio": 459053.11
      }
    }
  ],
  "spec": {
    "id": "fire-planner",
    "version": "1.0.0",
    "schema": {
      "type": "object",
      "properties": {
        "currentAge": {
          "type": "integer",
          "minimum": 16,
          "maximum": 80
        },
        "currentPortfolio": {
          "type": "number",
          "minimum": 0,
          "description": "What you have invested today"
        },
        "annualIncome": {
          "type": "number",
          "minimum": 0,
          "description": "Take-home income per year"
        },
        "annualSpending": {
          "type": "number",
          "minimum": 0,
          "description": "What you spend per year today"
        },
        "retirementSpending": {
          "type": "number",
          "minimum": 0,
          "description": "What you want to spend each year in retirement, in today's money"
        },
        "nominalReturnPct": {
          "type": "number",
          "minimum": 0,
          "maximum": 20,
          "description": "Expected investment return before inflation"
        },
        "inflationPct": {
          "type": "number",
          "minimum": 0,
          "maximum": 20
        },
        "swrPct": {
          "type": "number",
          "minimum": 0.5,
          "maximum": 10,
          "description": "Safe withdrawal rate — the 4% rule is the usual starting point"
        },
        "pensionAnnual": {
          "type": "number",
          "minimum": 0,
          "description": "State or workplace pension you expect each year"
        },
        "targetRetirementAge": {
          "type": "integer",
          "minimum": 30,
          "maximum": 90
        },
        "horizonYears": {
          "type": "integer",
          "minimum": 1,
          "maximum": 60
        },
        "annualContribution": {
          "type": "number",
          "readOnly": true
        },
        "savingsRatePct": {
          "type": "number",
          "readOnly": true
        },
        "realReturnPct": {
          "type": "number",
          "readOnly": true
        },
        "fiNumber": {
          "type": "number",
          "readOnly": true
        },
        "coastNumber": {
          "type": "number",
          "readOnly": true
        },
        "projection": {
          "type": "array",
          "readOnly": true,
          "items": {
            "type": "object",
            "properties": {
              "year": {
                "type": "integer"
              },
              "age": {
                "type": "integer"
              },
              "contributed": {
                "type": "number"
              },
              "portfolio": {
                "type": "number"
              },
              "target": {
                "type": "number"
              }
            }
          }
        },
        "fiAge": {
          "type": "integer",
          "readOnly": true,
          "description": "Age the projection first reaches the FI number; 0 if it never does"
        },
        "yearsToFi": {
          "type": "integer",
          "readOnly": true
        },
        "fiReached": {
          "type": "boolean",
          "readOnly": true
        },
        "finalPortfolio": {
          "type": "number",
          "readOnly": true
        },
        "sustainableWithdrawal": {
          "type": "number",
          "readOnly": true
        }
      },
      "required": [
        "currentAge",
        "annualIncome",
        "annualSpending",
        "retirementSpending"
      ]
    },
    "library": {
      "layers": [
        {
          "define": "( $grow := function($start, $contribution, $rate, $years) { $rate = 0 ? $start + $contribution * $years : $start * $power(1 + $rate, $years) + $contribution * ($power(1 + $rate, $years) - 1) / $rate }; [\"grow\"] )"
        }
      ]
    },
    "defaultValues": [
      {
        "path": "$",
        "expr": "{\"currentAge\": 30, \"currentPortfolio\": 100000, \"annualIncome\": 100000, \"annualSpending\": 60000, \"retirementSpending\": 60000, \"nominalReturnPct\": 7, \"inflationPct\": 3, \"swrPct\": 4, \"pensionAnnual\": 0, \"targetRetirementAge\": 60, \"horizonYears\": 40}"
      }
    ],
    "derivations": [
      {
        "path": "$.annualContribution",
        "expr": "$round(annualIncome - annualSpending, 2)"
      },
      {
        "path": "$.savingsRatePct",
        "expr": "annualIncome <= 0 ? 0 : $round((annualIncome - annualSpending) / annualIncome * 100, 1)"
      },
      {
        "path": "$.realReturnPct",
        "expr": "$round(((1 + nominalReturnPct / 100) / (1 + inflationPct / 100) - 1) * 100, 4)"
      },
      {
        "path": "$.fiNumber",
        "expr": "$max([0, $round((retirementSpending - pensionAnnual) / (swrPct / 100), 2)])"
      },
      {
        "path": "$.coastNumber",
        "expr": "( $n := targetRetirementAge - currentAge; $n <= 0 ? fiNumber : $round(fiNumber / $power(1 + realReturnPct / 100, $n), 2) )"
      },
      {
        "path": "$.projection",
        "expr": "$map([0..horizonYears], function($y) { { \"year\": $y, \"age\": currentAge + $y, \"contributed\": $round(currentPortfolio + annualContribution * $y, 2), \"portfolio\": $round($grow(currentPortfolio, annualContribution, realReturnPct / 100, $y), 2), \"target\": fiNumber } })"
      },
      {
        "path": "$.fiAge",
        "expr": "( $hits := $map(projection, function($p) { $p.portfolio >= $p.target ? $p.age : 0 })[$ > 0]; $count($hits) = 0 ? 0 : $min($hits) )"
      },
      {
        "path": "$.fiReached",
        "expr": "fiAge > 0"
      },
      {
        "path": "$.yearsToFi",
        "expr": "fiAge > 0 ? fiAge - currentAge : 0"
      },
      {
        "path": "$.finalPortfolio",
        "expr": "( $p := $map(projection, function($r) { $r.portfolio }); $i := $count($p) - 1; $p[$i] )"
      },
      {
        "path": "$.sustainableWithdrawal",
        "expr": "$round(finalPortfolio * swrPct / 100, 2)"
      }
    ],
    "constraints": [
      {
        "id": "swr-positive",
        "expr": "swrPct > 0",
        "message": "The withdrawal rate must be above zero — it is what turns a pot into an income",
        "policy": "rollback"
      },
      {
        "id": "retire-after-now",
        "expr": "targetRetirementAge > currentAge",
        "message": "Target retirement age must be later than your current age",
        "policy": "rollback"
      },
      {
        "id": "spending-within-income",
        "expr": "annualSpending <= annualIncome",
        "message": "You are spending more than you earn, so the portfolio is being drawn down rather than built",
        "policy": "flag"
      }
    ],
    "viewDefinition": {
      "renderer": "builtin",
      "defaultView": "main",
      "views": [
        {
          "id": "main",
          "label": "FIRE planner",
          "layout": "vertical",
          "components": [
            {
              "id": "assumptions",
              "type": "alert",
              "variant": "info",
              "label": "This is a projection from your assumptions",
              "text": "Everything here follows from the return, inflation and withdrawal rate you choose. Real markets do not deliver a steady return, and the order of good and bad years matters as much as the average. Figures are in today's money throughout — the projection grows the portfolio at the real return, not the nominal one. Not financial advice."
            },
            {
              "id": "todaySet",
              "type": "fieldSet",
              "legend": "Where you are now",
              "components": [
                {
                  "id": "ageField",
                  "type": "numericField",
                  "label": "Your age",
                  "bind": "$.currentAge",
                  "placeholder": "30"
                },
                {
                  "id": "portfolioField",
                  "type": "numericField",
                  "label": "Invested today",
                  "bind": "$.currentPortfolio",
                  "placeholder": "100000"
                },
                {
                  "id": "incomeField",
                  "type": "numericField",
                  "label": "Take-home income / yr",
                  "bind": "$.annualIncome",
                  "placeholder": "100000"
                },
                {
                  "id": "spendingField",
                  "type": "numericField",
                  "label": "Spending / yr",
                  "bind": "$.annualSpending",
                  "placeholder": "60000"
                }
              ]
            },
            {
              "id": "targetSet",
              "type": "fieldSet",
              "legend": "What you are aiming at",
              "components": [
                {
                  "id": "retSpendField",
                  "type": "numericField",
                  "label": "Retirement spending / yr (today's money)",
                  "bind": "$.retirementSpending",
                  "placeholder": "60000"
                },
                {
                  "id": "pensionField",
                  "type": "numericField",
                  "label": "State or workplace pension / yr",
                  "bind": "$.pensionAnnual",
                  "placeholder": "0"
                },
                {
                  "id": "targetAgeField",
                  "type": "numericField",
                  "label": "Target retirement age (for Coast FI)",
                  "bind": "$.targetRetirementAge",
                  "placeholder": "60"
                },
                {
                  "id": "swrField",
                  "type": "sliderField",
                  "label": "Safe withdrawal rate (%)",
                  "bind": "$.swrPct",
                  "min": 2,
                  "max": 8,
                  "step": 0.1
                }
              ]
            },
            {
              "id": "marketSet",
              "type": "fieldSet",
              "legend": "Market assumptions",
              "components": [
                {
                  "id": "returnField",
                  "type": "sliderField",
                  "label": "Nominal return per year (%)",
                  "bind": "$.nominalReturnPct",
                  "min": 0,
                  "max": 15,
                  "step": 0.5
                },
                {
                  "id": "inflationField",
                  "type": "sliderField",
                  "label": "Inflation per year (%)",
                  "bind": "$.inflationPct",
                  "min": 0,
                  "max": 10,
                  "step": 0.5
                },
                {
                  "id": "horizonField",
                  "type": "sliderField",
                  "label": "Project this many years",
                  "bind": "$.horizonYears",
                  "min": 5,
                  "max": 60,
                  "step": 1
                }
              ]
            },
            {
              "id": "sep1",
              "type": "separatorLine"
            },
            {
              "id": "headline",
              "type": "group",
              "layout": "horizontal",
              "components": [
                {
                  "id": "fiAgeTile",
                  "type": "statTile",
                  "label": "Financially independent at",
                  "bind": "$.fiAge",
                  "format": "number",
                  "caption": "0 means not within your projection"
                },
                {
                  "id": "yearsTile",
                  "type": "statTile",
                  "label": "Years to get there",
                  "bind": "$.yearsToFi",
                  "format": "number"
                },
                {
                  "id": "fiNumberTile",
                  "type": "statTile",
                  "label": "The number you need",
                  "bind": "$.fiNumber",
                  "format": "number",
                  "caption": "spending divided by your withdrawal rate"
                },
                {
                  "id": "savingsRateTile",
                  "type": "statTile",
                  "label": "Savings rate",
                  "bind": "$.savingsRatePct",
                  "format": "number",
                  "caption": "% of take-home saved"
                }
              ]
            },
            {
              "id": "secondary",
              "type": "group",
              "layout": "horizontal",
              "components": [
                {
                  "id": "realReturnTile",
                  "type": "statTile",
                  "label": "Real return",
                  "bind": "$.realReturnPct",
                  "format": "number",
                  "caption": "% after inflation — the one that matters"
                },
                {
                  "id": "coastTile",
                  "type": "statTile",
                  "label": "Coast FI number",
                  "bind": "$.coastNumber",
                  "format": "number",
                  "caption": "have this and you can stop contributing"
                },
                {
                  "id": "contributionTile",
                  "type": "statTile",
                  "label": "Saved per year",
                  "bind": "$.annualContribution",
                  "format": "number"
                },
                {
                  "id": "withdrawalTile",
                  "type": "statTile",
                  "label": "Income at the end",
                  "bind": "$.sustainableWithdrawal",
                  "format": "number",
                  "caption": "final portfolio at your withdrawal rate"
                }
              ]
            },
            {
              "id": "sep2",
              "type": "separatorLine"
            },
            {
              "id": "projectionChart",
              "type": "dataChart",
              "label": "Portfolio against the number you need (today's money)",
              "chartType": "line",
              "bind": "$.projection",
              "chartX": "age",
              "chartSeries": [
                {
                  "field": "portfolio",
                  "label": "Portfolio"
                },
                {
                  "field": "target",
                  "label": "FI number"
                },
                {
                  "field": "contributed",
                  "label": "Contributed"
                }
              ]
            },
            {
              "id": "projectionTable",
              "type": "dataTable",
              "label": "Year by year",
              "bind": "$.projection",
              "tableColumns": [
                {
                  "field": "year",
                  "header": "Year",
                  "width": "12%"
                },
                {
                  "field": "age",
                  "header": "Age",
                  "width": "12%"
                },
                {
                  "field": "contributed",
                  "header": "Put in",
                  "format": "number",
                  "width": "25%"
                },
                {
                  "field": "portfolio",
                  "header": "Portfolio",
                  "format": "number",
                  "width": "26%"
                },
                {
                  "field": "target",
                  "header": "Target",
                  "format": "number",
                  "width": "25%"
                }
              ],
              "pageSize": 15
            }
          ]
        }
      ]
    },
    "tests": [
      {
        "description": "age 30 with 100k invested, saving 40k of 100k, 7% nominal against 3% inflation, 4% withdrawal rate",
        "given": {
          "$.currentAge": 30,
          "$.currentPortfolio": 100000,
          "$.annualIncome": 100000,
          "$.annualSpending": 60000,
          "$.retirementSpending": 60000,
          "$.nominalReturnPct": 7,
          "$.inflationPct": 3,
          "$.swrPct": 4
        },
        "expect": {
          "$.annualContribution": 40000,
          "$.savingsRatePct": 40,
          "$.realReturnPct": 3.8835,
          "$.fiNumber": 1500000,
          "$.coastNumber": 478293.04,
          "$.projection[0].portfolio": 100000,
          "$.projection[1].portfolio": 143883.5,
          "$.projection[22].portfolio": 1582779.59,
          "$.fiAge": 52,
          "$.yearsToFi": 22,
          "$.fiReached": true,
          "$.finalPortfolio": 4157295.48,
          "$.sustainableWithdrawal": 166291.82
        }
      },
      {
        "description": "saving 60% instead of 40% brings independence forward five years",
        "given": {
          "$.annualSpending": 40000
        },
        "expect": {
          "$.annualContribution": 60000,
          "$.savingsRatePct": 60,
          "$.fiNumber": 1500000,
          "$.fiAge": 47,
          "$.yearsToFi": 17
        }
      },
      {
        "description": "a 12,000 pension cuts the number you need by exactly the pension capitalised at the withdrawal rate",
        "given": {
          "$.pensionAnnual": 12000
        },
        "expect": {
          "$.fiNumber": 1200000,
          "$.coastNumber": 382634.43,
          "$.fiAge": 48,
          "$.yearsToFi": 18
        }
      },
      {
        "description": "spending everything you earn — the pot still compounds, but never reaches the target in the horizon",
        "given": {
          "$.annualSpending": 100000
        },
        "expect": {
          "$.annualContribution": 0,
          "$.savingsRatePct": 0,
          "$.fiAge": 0,
          "$.fiReached": false,
          "$.yearsToFi": 0,
          "$.finalPortfolio": 459053.11
        }
      }
    ]
  }
}