{
  "id": "300k-mortgage",
  "version": "b86bad2c1204",
  "status": "published",
  "name": "300K Mortgage Calculator",
  "question": "300k mortgage: what is the payment?",
  "summary": "Works out the monthly payment and total interest on a $300,000 mortgage at your rate over 30 years or any term, with the payments over 15, 20 and 30 years side by side.",
  "category": "finance",
  "subcategory": "loans",
  "url": "https://www.acalculator.org/finance/300k-mortgage-calculator",
  "markdown": "https://www.acalculator.org/finance/300k-mortgage-calculator.md",
  "kind": "function",
  "method": "Monthly rate r = yearly rate ÷ 1,200 and n = years × 12 payments. Payment M = L × r ÷ (1 − (1 + r)^−n), or L ÷ n at 0%. Total interest = M × n − L.",
  "assumptions": [
    "A fixed rate for the whole term, monthly payments, and no extra payments or fees.",
    "The payment is principal and interest only: property tax, insurance, HOA dues and mortgage insurance are extra."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "loan": {
        "title": "Loan amount",
        "description": "The amount you borrow: $300,000 on this page, or any amount.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 1000,
        "maximum": 1000000000
      },
      "rate": {
        "title": "Interest rate",
        "description": "The fixed yearly rate your lender quotes. The monthly rate is this ÷ 12.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 0,
        "maximum": 30
      },
      "years": {
        "title": "Loan term (years)",
        "description": "The length of the mortgage, 30 years by default.",
        "type": "integer",
        "minimum": 1,
        "maximum": 50
      }
    }
  },
  "outputs": {
    "payment": {
      "label": "Monthly payment",
      "description": "Principal and interest each month.",
      "format": "money"
    },
    "principal": {
      "label": "Loan amount",
      "description": "The amount borrowed.",
      "format": "money"
    },
    "interest": {
      "label": "Total interest",
      "description": "Every payment added up, minus the loan.",
      "format": "money"
    },
    "total": {
      "label": "Total of payments",
      "description": "The loan plus the total interest.",
      "format": "money"
    },
    "pay15": {
      "label": "Payment over 15 years",
      "description": "The same loan and rate over 15 years.",
      "format": "money"
    },
    "pay20": {
      "label": "Payment over 20 years",
      "description": "The same loan and rate over 20 years.",
      "format": "money"
    },
    "pay30": {
      "label": "Payment over 30 years",
      "description": "The same loan and rate over 30 years.",
      "format": "money"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "loan": 300000,
      "rate": 6.5,
      "years": 30
    },
    "outputs": {
      "payment": 1896.2040704788913,
      "principal": 300000,
      "interest": 382633.4653724008,
      "total": 682633.4653724008,
      "pay15": 2613.3220958920842,
      "pay20": 2236.7194065452913,
      "pay30": 1896.2040704788913
    },
    "text": "A 30-year loan of $300,000.00 at 6.5% costs $1,896.20 a month, with $382,633.47 of interest in total."
  },
  "examples": [
    {
      "given": {
        "loan": 300000,
        "rate": 6.5,
        "years": 30
      },
      "expect": {
        "payment": 1896.204070478896,
        "interest": 382633.46537240257,
        "pay15": 2613.322095892097,
        "pay20": 2236.7194065453
      },
      "source": "OpenStax, Contemporary Mathematics, section 6.12 Renting and Homeownership: monthly mortgage payment pmt = P × (r/12) × (1 + r/12)^(12t) ÷ ((1 + r/12)^(12t) − 1); total paid = pmt × 12 × t; Example 6.111: $99,596 at 5.35% for 30 years, $556.16 a month (rounded up). https://openstax.org/books/contemporary-mathematics/pages/6-12-renting-and-homeownership (retrieved 2026-10-18); Python 3 in docs/progress/WP-124.md"
    },
    {
      "given": {
        "loan": 300000,
        "rate": 7,
        "years": 30
      },
      "expect": {
        "payment": 1995.907485537547,
        "interest": 418526.6947935169
      },
      "source": "OpenStax, Contemporary Mathematics, section 6.12 Renting and Homeownership: monthly mortgage payment pmt = P × (r/12) × (1 + r/12)^(12t) ÷ ((1 + r/12)^(12t) − 1); total paid = pmt × 12 × t; Example 6.111: $99,596 at 5.35% for 30 years, $556.16 a month (rounded up). https://openstax.org/books/contemporary-mathematics/pages/6-12-renting-and-homeownership (retrieved 2026-10-18); Python 3 in docs/progress/WP-124.md"
    },
    {
      "given": {
        "loan": 99596,
        "rate": 5.35,
        "years": 30
      },
      "expect": {
        "payment": 556.1577033763834
      },
      "source": "OpenStax, Contemporary Mathematics, section 6.12 Renting and Homeownership: monthly mortgage payment pmt = P × (r/12) × (1 + r/12)^(12t) ÷ ((1 + r/12)^(12t) − 1); total paid = pmt × 12 × t; Example 6.111: $99,596 at 5.35% for 30 years, $556.16 a month (rounded up). https://openstax.org/books/contemporary-mathematics/pages/6-12-renting-and-homeownership (retrieved 2026-10-18)"
    },
    {
      "given": {
        "loan": 300000,
        "rate": 0,
        "years": 30
      },
      "expect": {
        "payment": 833.3333333333334,
        "interest": 0
      },
      "source": "hand calculation in content.mdx: 300,000 ÷ 360 = 833.33"
    }
  ],
  "sources": [
    "OpenStax, Contemporary Mathematics, section 6.12 Renting and Homeownership: the monthly mortgage payment pmt = P × (r/12) × (1 + r/12)^(12t) ÷ ((1 + r/12)^(12t) − 1) for principal P, yearly rate r and t years; total paid = pmt × 12 × t; Example 6.111, $99,596 at 5.35% for 30 years, $556.16 a month. Retrieved 2026-10-18. https://openstax.org/books/contemporary-mathematics/pages/6-12-renting-and-homeownership"
  ],
  "related": [
    "mortgage",
    "50-year-mortgage",
    "40-year-mortgage",
    "mortgage-comparison"
  ],
  "changelog": []
}