Calq.

Mortgage Calculator

Calculate your monthly mortgage payments based on the loan amount, interest rate, and term.

Results

Monthly Payment
Total Paid
Total Interest Paid

Introduction

Calq’s Mortgage Calculator estimates your monthly mortgage payment for a standard amortizing (annuity) home loan. It’s ideal for homebuyers comparing options, owners considering a refinance, and anyone who wants to see how loan size, interest rate, and term affect costs. Results focus on principal and interest (P&I). Your real monthly housing cost may be higher once taxes, insurance, and other fees are added.

How it works

  1. Enter the loan principal (the amount you borrow after any down payment).
  2. Enter the annual interest rate as a percentage (for example, 6.25).
  3. Enter the term in years (for example, 30).
  4. Click calculate to see the monthly payment, total paid over the term, and total interest.
  5. Adjust any input to compare scenarios (larger down payment, shorter term, different rates).

Inputs explained

  • Principal: The loan amount you will actually finance. Larger principal increases the monthly payment and the total interest over time. Use local currency (e.g., $, £, €). Use a period for decimals (for example, 250,000.00).
  • Interest rate: The nominal annual rate of the mortgage (not APR). Enter as a percentage, such as 5.75. Even small rate changes significantly affect costs because interest compounds monthly.
  • Term (years): How long you will repay the loan. Common terms are 15, 20, or 30 years. Shorter terms raise the monthly payment but reduce total interest; longer terms do the opposite.

Results and interpretation

  • Monthly payment: Your fixed principal-and-interest payment due each month. Early payments are mostly interest; later payments are mostly principal.
  • Total payment: Monthly payment multiplied by the number of months in the term. This is the full amount repaid over the life of the loan.
  • Total interest: Total payment minus the original principal. This shows the cost of borrowing.

Method and assumptions

This calculator models a standard fixed-rate amortizing (annuity) mortgage with equal monthly payments.

Formula:


Monthly payment = P × \[r × (1 + r)^n] ÷ \[(1 + r)^n − 1]

Where:

  • P = principal
  • r = monthly interest rate = annual rate ÷ 12 (as a decimal)
  • n = total number of payments = term in years × 12

Assumptions:

  • Interest compounds monthly.
  • Payments are assumed on time with no extra principal prepayments.
  • Adjustable-rate mortgages (ARMs) are not fully modeled; using a single rate approximates the initial fixed period only.
  • Taxes, homeowners insurance, HOA dues, mortgage insurance, and fees are excluded.
  • Rounding may cause minor cent-level differences.

Mortgage basics and context

  • Cost components beyond P&I may include property taxes, homeowners insurance, mortgage insurance (if your down payment is small), and HOA fees. These vary by region and lender.
  • Rate types:
    • Fixed-rate: Same interest rate for the entire term; payment stability.
    • Adjustable-rate (ARM): Rate can change after an initial fixed period; payments may rise or fall.
  • Typical terms: 15-30 years for many markets. Short terms build equity faster and reduce interest; long terms lower the monthly payment.
  • Affordability guidelines: Lenders often look at your debt-to-income ratio. Common rules of thumb (which vary by country and lender) suggest keeping housing costs within a conservative share of your gross income. Treat such rules as general guidance, not guarantees.

Tips and strategies

  • Shop the rate: Request quotes from multiple lenders on the same day and compare the full cost, not just the headline rate.
  • Consider points and fees: “Buying points” lowers the rate for an upfront cost. Calculate the break-even period before paying for points.
  • Choose an appropriate term: Shorter terms save interest but require higher monthly payments. Ensure you keep an emergency fund.
  • Make extra principal payments: Even small extra amounts toward principal can shorten the term and reduce total interest. Confirm your lender applies extra payments to principal.
  • Improve your profile: A higher credit score, larger down payment, and lower debt can qualify you for better rates.
  • Plan for all-in costs: Add estimates for taxes, insurance, HOA dues, and mortgage insurance to understand your full monthly housing cost.

Example calculation (USD)

  • Principal: $350,000
  • Interest rate: 6.50% annual
  • Term: 30 years
  • Monthly payment (P&I): $2,212.24
  • Total payment over 30 years: $796,405.71
  • Total interest: $446,405.71

Interpretation: Extending to 30 years keeps the monthly payment lower, but total interest paid over time is significant. Reducing the rate or shortening the term can materially cut total interest.

Example calculation (GBP)

  • Principal: £250,000
  • Interest rate: 5.25% annual
  • Term: 25 years
  • Monthly payment (P&I): £1,498.12
  • Total payment over 25 years: £449,435.79
  • Total interest: £199,435.79

Interpretation: A shorter term than 30 years increases the monthly payment but reduces the overall interest cost.

Frequently asked questions

  1. What is an “annuity” mortgage?
    It is a fully amortizing loan repaid with equal monthly payments. Each payment covers that month’s interest plus a portion of principal, so the balance falls to zero by the end of the term.

  2. Does this calculator include taxes and insurance?
    No. It focuses on principal and interest. Property taxes, homeowners insurance, HOA dues, and mortgage insurance (if applicable) are separate and vary by location and lender.

  3. What’s the difference between interest rate and APR?
    The interest rate is the cost of borrowing expressed annually and used in the amortization formula. APR attempts to reflect the total cost of credit, including certain fees. Use the rate for calculating monthly payments; use APR for comparing overall loan cost.

  4. Can I model an adjustable-rate mortgage (ARM)?
    You can approximate the initial fixed period by entering its rate, but future changes are not modeled here. For full ARM projections, use a specialized ARM calculator or ask your lender for scenarios.

  5. Is it better to make biweekly payments?
    Biweekly plans effectively add about one extra monthly payment per year, reducing total interest and term. You can often achieve a similar result by making one extra principal payment annually or rounding up monthly-just ensure the lender applies extra amounts to principal.

  6. What happens if the interest rate is 0%?
    At 0%, the monthly payment equals principal divided by the number of months in the term, with no interest cost.

Summary

Use the Mortgage Calculator to understand how loan size, interest rate, and term shape your monthly payment and total borrowing cost. Compare scenarios, factor in all-in housing expenses, and avoid stretching your budget. Results are estimates for educational purposes, not financial advice. Use the calculator above with your details to find a payment that fits your plan, then confirm terms and total costs with your lender.