Coast-FIRE number API

Compute the Coast-FIRE number — the amount needed today that, left untouched, compounds to the full FIRE number by retirement — via coastNumber = fireNumber/(1+realReturn)^(retirementAge−currentAge), returning whether current savings already coast plus surplus/shortfall. Answers 'have I hit coast FIRE','how much do I need now to coast to retirement','can I stop contributing and still retire'.

Price$0.01per request

MethodPOST

Route/v1/calc/pf-coast-fire

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

calccoast-firefireretirementcompoundfinancial-independencepersonal-financediscounting

API URLhttps://x402.hexl.dev/v1/calc/pf-coast-fire

Integration docs

Example request

{
  "annualExpenses": 40000,
  "currentAge": 30,
  "retirementAge": 60,
  "realReturnPercent": 5,
  "currentSavings": 150000
}

Example response

{
  "formula": "coastNumber = fireNumber / (1+realReturn)^(retirementAge−currentAge)",
  "coastFireNumber": 231377.45,
  "fireNumber": 1000000,
  "yearsToRetirement": 30,
  "currentSavings": 150000,
  "hasReachedCoastFire": false,
  "surplusOrShortfall": -81377.45,
  "rating": "still accumulating",
  "breakdown": {
    "annualExpenses": 40000,
    "currentAge": 30,
    "retirementAge": 60,
    "realReturnPercent": 5,
    "safeWithdrawalRatePercent": 4
  }
}

Input schema

{
  "type": "object",
  "required": [
    "annualExpenses",
    "currentAge",
    "retirementAge"
  ],
  "properties": {
    "annualExpenses": {
      "type": "number",
      "examples": [
        40000
      ]
    },
    "currentAge": {
      "type": "number",
      "examples": [
        30
      ]
    },
    "retirementAge": {
      "type": "number",
      "examples": [
        60
      ]
    },
    "realReturnPercent": {
      "type": "number",
      "description": "default 5",
      "examples": [
        5
      ]
    },
    "safeWithdrawalRatePercent": {
      "type": "number",
      "description": "default 4",
      "examples": [
        4
      ]
    },
    "currentSavings": {
      "type": "number",
      "examples": [
        150000
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}