About This Mortgage Calculator

What it does

Quickly estimates your monthly mortgage payment and summarizes the interest vs. principal breakdown (first month), plus total interest and total paid over the life of the loan.

Inputs

• Loan Amount — total amount financed
• Annual Interest Rate — APR as a percentage
• Term — loan length in years

Formulas

• Monthly rate: r = (annualRate / 100) / 12
• Total payments: n = years * 12
• Monthly payment (amortized): M = P * r * (1 + r)^n / ((1 + r)^n - 1)
  • If r = 0, then M = P / n
• Total paid: Total = M * n
• Total interest: Interest = Total - P
• First month interest: P * r
• First month principal: M - (P * r)

Notes

• This tool models principal and interest only. Taxes, insurance, HOA dues, and PMI are not included.
• Actual lender terms, compounding conventions, and fees may vary.
• For a full amortization schedule, export data to a spreadsheet or use a specialized schedule tool.

Example

For a $300,000 loan at 6.5% APR over 30 years:

• Monthly payment ≈ $1,896.20
• First month interest ≈ $1,625.00
• First month principal ≈ $271.20
• Total paid ≈ $682,632.00
• Total interest ≈ $382,632.00

Results are rounded; your actual numbers may differ slightly based on lender specifics.