Compound Mint Money Calculator

Use first when a user asks a money math question in plain words, such as "how much will $500 a month grow in 20 years?", "when can I retire if I spend $40,000 a year?", "how long to pay off $5,000 on my credit card at 24% paying $200 a month?", "how much do I need to save each month to have $50,000 in 5 years?", "how long to double my money at 8%?" or "am I getting my full 401(k) match?". Reads the amounts, rates, ages and years from the question, picks the matching Compound Mint calculator (compound interest, Rule of 72, FIRE number, Coast FIRE, 401(k) match, debt payoff, savings goal), runs it and returns the answer with what it understood, the explanation, the assumptions, source_page to cite and related_reading. When a needed number is missing it returns status need_more_info with the exact question to ask the user.

{
  "type": "object",
  "properties": {
    "question": {
      "type": "string",
      "description": "The money question in plain words, with any amounts, rates, ages and years, e.g. \"How much will $500 a month grow in 20 years at 8%?\""
    }
  },
  "required": [
    "question"
  ]
}

Use when a user asks how much money will grow, e.g. "how much will $500 a month grow in 20 years?", "what will $10,000 be worth in 10 years at 7%?" or "how much interest will I earn?". Future value of a starting amount plus optional monthly contributions at a yearly rate, with total contributed and total interest. Compounding is monthly by default (annually, quarterly, semiannually or daily on request). Returns a plain-English explanation, the assumptions and the matching Compound Mint calculator page. Example: $10,000 at 7% for 10 years compounded annually = $19,671.51.

{
  "type": "object",
  "properties": {
    "principal": {
      "type": "number",
      "description": "Starting amount in USD (default 0).",
      "minimum": 0
    },
    "monthly_contribution": {
      "type": "number",
      "description": "USD added every month (default 0).",
      "minimum": 0
    },
    "annual_rate": {
      "type": "number",
      "description": "Yearly rate in percent, e.g. 7 (default 8).",
      "minimum": 0,
      "maximum": 50
    },
    "years": {
      "type": "number",
      "description": "Years, up to 100.",
      "minimum": 0.0833,
      "maximum": 100
    },
    "compounding": {
      "type": "string",
      "enum": [
        "monthly",
        "annually",
        "quarterly",
        "semiannually",
        "daily"
      ],
      "description": "How often interest compounds (default monthly)."
    },
    "contribution_timing": {
      "type": "string",
      "enum": [
        "end",
        "beginning"
      ],
      "description": "Deposits at the end (default) or beginning of each month."
    },
    "show_yearly": {
      "type": "boolean",
      "description": "Include a year by year table."
    }
  },
  "required": [
    "years"
  ]
}

Use when a user asks how long it takes to double money ("how long to double my money at 8%?") or what return doubles it in a number of years. How long money takes to double at a yearly rate (send annual_rate), or the rate needed to double in a number of years (send years). Gives the Rule of 72 estimate and the exact figure. Example: at 8% money doubles in about 9 years.

{
  "type": "object",
  "properties": {
    "annual_rate": {
      "type": "number",
      "description": "Yearly return in percent, e.g. 8.",
      "minimum": 0.01,
      "maximum": 100
    },
    "years": {
      "type": "number",
      "description": "Years to double, to get the rate needed.",
      "minimum": 0.1,
      "maximum": 200
    }
  }
}

Use when a user asks about Coast FIRE, e.g. "what is my Coast FIRE number at 30?" or "can I stop saving for retirement and let it grow?". FIRE number (yearly spending / withdrawal rate) and Coast FIRE number: what you need invested now so growth alone reaches your FIRE number by retirement age. Add current savings and a monthly contribution to see the gap and the age you reach Coast FIRE. Uses a real (after inflation) return, 7% by default; same math as the Compound Mint Coast FIRE calculator.

{
  "type": "object",
  "properties": {
    "current_age": {
      "type": "number",
      "description": "Age now."
    },
    "retirement_age": {
      "type": "number",
      "description": "Age you want to retire."
    },
    "annual_spending": {
      "type": "number",
      "description": "Yearly spending in retirement in today's USD (or send fire_number)."
    },
    "fire_number": {
      "type": "number",
      "description": "Total needed to retire in USD (instead of annual_spending)."
    },
    "withdrawal_rate": {
      "type": "number",
      "description": "Safe withdrawal rate percent (default 4)."
    },
    "annual_return": {
      "type": "number",
      "description": "Real yearly return percent after inflation (default 7)."
    },
    "current_savings": {
      "type": "number",
      "description": "USD invested now (default 0)."
    },
    "monthly_contribution": {
      "type": "number",
      "description": "USD invested each month (default 0)."
    }
  },
  "required": [
    "current_age",
    "retirement_age"
  ]
}

Use when a user asks when they can retire or how much they need to retire, e.g. "when can I retire if I invest $1,500 a month?", "what is my FIRE number if I spend $40,000 a year?" or "how many years until I can stop working?". Returns the FIRE number (yearly spending / withdrawal rate, 25 times spending at 4%) and, from current savings and a monthly contribution, the months and years to reach it and the age if current_age is given. Uses a real (after inflation) return, 7% by default; same math as the Compound Mint FIRE number calculator.

{
  "type": "object",
  "properties": {
    "annual_spending": {
      "type": "number",
      "description": "Yearly spending in retirement in today's USD (or send fire_number)."
    },
    "fire_number": {
      "type": "number",
      "description": "Total needed to retire in USD (instead of annual_spending)."
    },
    "current_savings": {
      "type": "number",
      "description": "USD invested now (default 0)."
    },
    "monthly_contribution": {
      "type": "number",
      "description": "USD invested each month (default 0)."
    },
    "withdrawal_rate": {
      "type": "number",
      "description": "Safe withdrawal rate percent (default 4)."
    },
    "annual_return": {
      "type": "number",
      "description": "Real yearly return percent after inflation (default 7)."
    },
    "current_age": {
      "type": "number",
      "description": "Optional age now, to show the age you reach it."
    }
  }
}

Use when a user asks how much to spend on the holidays or on Christmas gifts, e.g. "how much should I budget for Christmas?", "can I afford $50 gifts for 8 people?" or "how much do I need to save each week for the holidays?". Adds gifts (people x budget per person), travel, food and decor; returns the total, its share of monthly take-home pay, weeks of saving needed, cash by the holidays and a spend limit (spend this, not more), plus the per-person gift budget that fits. Same math as the compoundmint.com holiday budget calculator. Educational only, not financial advice.

{
  "type": "object",
  "properties": {
    "people": {
      "type": "number",
      "description": "People on the gift list.",
      "minimum": 0,
      "maximum": 500
    },
    "per_person_budget": {
      "type": "number",
      "description": "Gift budget per person in USD.",
      "minimum": 0
    },
    "travel": {
      "type": "number",
      "description": "Travel in USD (default 0).",
      "minimum": 0
    },
    "food": {
      "type": "number",
      "description": "Food and hosting in USD (default 0).",
      "minimum": 0
    },
    "decor": {
      "type": "number",
      "description": "Decor, wrapping and cards in USD (default 0).",
      "minimum": 0
    },
    "monthly_income": {
      "type": "number",
      "description": "Monthly take-home pay in USD (optional, for the percent of income).",
      "minimum": 0
    },
    "already_saved": {
      "type": "number",
      "description": "USD already saved for the holidays (default 0).",
      "minimum": 0
    },
    "weekly_savings": {
      "type": "number",
      "description": "USD you can save each week (default 0).",
      "minimum": 0
    },
    "weeks_left": {
      "type": "number",
      "description": "Weeks until the holidays (default: full weeks until December 25).",
      "minimum": 0,
      "maximum": 104
    }
  },
  "required": [
    "people",
    "per_person_budget"
  ]
}

Use when a user asks about a 401(k) employer match, e.g. "am I getting my full 401(k) match?", "how much is my employer match worth?" or "what percent should I put in to get the full match?". Your yearly 401(k) contribution, the employer match, the percent needed for the full match and any match left unclaimed, using 2026 IRS limits ($24,500 employee, catch-up at 50 and over and at 60 to 63, $72,000 overall, $360,000 pay cap). Supports a two tier formula such as 100% up to 3% then 50% of the next 2%. Optional years and annual_return project the balance.

{
  "type": "object",
  "properties": {
    "salary": {
      "type": "number",
      "description": "Yearly pay in USD."
    },
    "contribution_percent": {
      "type": "number",
      "description": "Percent of pay you contribute, e.g. 4."
    },
    "match_percent": {
      "type": "number",
      "description": "Employer match rate percent, e.g. 50 for 50 cents per dollar (default 50)."
    },
    "match_up_to_percent": {
      "type": "number",
      "description": "Percent of pay the match applies to (default 6)."
    },
    "tier2_match_percent": {
      "type": "number",
      "description": "Optional second tier match rate percent."
    },
    "tier2_up_to_percent": {
      "type": "number",
      "description": "Optional second tier size, percent of pay."
    },
    "age": {
      "type": "number",
      "description": "Optional age, for catch-up limits."
    },
    "years": {
      "type": "number",
      "description": "Optional years to project."
    },
    "annual_return": {
      "type": "number",
      "description": "Yearly return percent for the projection (default 7)."
    }
  },
  "required": [
    "salary",
    "contribution_percent"
  ]
}

Use when a user asks how long it takes to pay off a credit card or loan, what payment clears it by a date, or avalanche vs snowball, e.g. "how long to pay off $5,000 at 24% paying $200 a month?" or "what payment pays off my credit card in 2 years?". One debt: months to pay off and total interest at a monthly payment, or the payment needed to be debt free in target_months. Several debts: send debts (each with name, balance, apr, min_payment) and extra_payment to compare the avalanche and snowball methods.

{
  "type": "object",
  "properties": {
    "balance": {
      "type": "number",
      "description": "What you owe in USD (one debt)."
    },
    "apr": {
      "type": "number",
      "description": "Yearly interest rate percent (one debt)."
    },
    "monthly_payment": {
      "type": "number",
      "description": "USD paid each month (or send target_months)."
    },
    "target_months": {
      "type": "number",
      "description": "Months to be debt free (or send monthly_payment)."
    },
    "debts": {
      "type": "array",
      "description": "Several debts, up to 20.",
      "items": {
        "type": "object",
        "properties": {
          "name": {
            "type": "string"
          },
          "balance": {
            "type": "number"
          },
          "apr": {
            "type": "number"
          },
          "min_payment": {
            "type": "number"
          }
        },
        "required": [
          "balance",
          "apr",
          "min_payment"
        ]
      }
    },
    "extra_payment": {
      "type": "number",
      "description": "USD a month on top of all minimums (several debts)."
    },
    "strategy": {
      "type": "string",
      "enum": [
        "avalanche",
        "snowball",
        "compare"
      ],
      "description": "Several debts: which method (default compare)."
    }
  }
}

Use when a user asks how much to save each month for a goal, e.g. "how much do I need to save each month to have $50,000 in 5 years?" or "how much a month to reach $1 million in 30 years?". Monthly amount to save to reach a target in a number of years at a yearly rate, counting money already saved. Example: $1,000,000 in 30 years at 8% needs about $671 a month.

{
  "type": "object",
  "properties": {
    "target_amount": {
      "type": "number",
      "description": "Goal in USD."
    },
    "years": {
      "type": "number",
      "description": "Years to reach it."
    },
    "annual_rate": {
      "type": "number",
      "description": "Yearly return percent (default 0, no growth)."
    },
    "current_savings": {
      "type": "number",
      "description": "USD already saved (default 0)."
    }
  },
  "required": [
    "target_amount",
    "years"
  ]
}

Lists every calculator tool with its inputs, an example and its REST endpoint.

{
  "type": "object",
  "properties": {}
}

Searches Compound Mint calculators and personal finance guides. Returns results with id, title and url; read one with fetch.

{
  "type": "object",
  "properties": {
    "query": {
      "type": "string",
      "description": "What to look for, e.g. coast fire or 401k match."
    }
  },
  "required": [
    "query"
  ]
}

Returns the text of one Compound Mint page by id (from search) or by URL.

{
  "type": "object",
  "properties": {
    "id": {
      "type": "string",
      "description": "An id from search, or a compoundmint.com URL."
    }
  },
  "required": [
    "id"
  ]
}