Mortgage Comparison Calculator
Side-by-Side Comparison
What Is a Mortgage Comparison Calculator?
A Mortgage Comparison Calculator is a tool that compares two mortgage options using the standard fixed-rate, fully amortizing payment formula. It solves a common problem: two loans can have different rates, terms, or loan amounts, so the lower monthly payment is not always the lower total cost.
This calculator takes three inputs for each loan option: loan amount, annual interest rate, and loan term in years. It then estimates the monthly payment, total interest, and total cost for both loans. It also shows the difference between Option 1 and Option 2 for each result.
A mortgage comparison calculator estimates how two fixed-rate mortgages compare by monthly payment, total interest, and total cost. Enter both loan amounts, rates, and terms to see which option costs more or less under the calculator’s principal-and-interest-only formula.
How the Mortgage Comparison Calculator Formula Works
The calculator uses a fixed-rate fully amortizing loan formula. “Fully amortizing” means the payment is designed to pay off the loan balance over the full term when every scheduled monthly payment is made. The calculator assumes 12 monthly payments per year.
In this formula, P is the loan amount. R is the annual interest rate as a percent. r is the monthly interest rate. t is the loan term in years. n is the total number of monthly payments. M is the estimated monthly principal and interest payment.
If the interest rate is 0%, the calculator uses a simpler payment method because there is no monthly interest charge.
After finding the monthly payment, the calculator estimates total cost and total interest.
For example, compare a $300,000 loan at 6.5% for 30 years with a $300,000 loan at 5.75% for 15 years. Option 1 has 360 monthly payments and an estimated monthly payment of $1,896.20. Its total cost is $682,633.47, and total interest is $382,633.47.
Option 2 has 180 monthly payments and an estimated monthly payment of $2,491.23. Its total cost is $448,421.45, and total interest is $148,421.45. The calculator then subtracts Option 2 from Option 1. In this example, Option 1 has a monthly payment difference of $-595.03, but it has $234,212.02 more total interest and $234,212.02 more total cost.
The calculator only compares principal and interest. It does not include property taxes, homeowners insurance, private mortgage insurance, closing costs, or lender fees.
How to Use the Mortgage Comparison Calculator: Step by Step
- Enter the Loan Amount ($) for Loan Option 1. This amount must be greater than zero.
- Enter the Annual Interest Rate (%) for Loan Option 1. The calculator accepts rates of 0 or higher.
- Enter the Loan Term (Years) for Loan Option 1. The term must be greater than zero.
- Enter the Loan Amount ($) for Loan Option 2. Use the same amount if you only want to compare rate or term differences.
- Enter the Annual Interest Rate (%) for Loan Option 2. This lets you compare two different rate offers.
- Enter the Loan Term (Years) for Loan Option 2. This lets you compare shorter and longer repayment periods.
- Select Calculate to see the side-by-side comparison. Select Reset to clear all fields and hide the results.
The output shows each loan’s monthly payment, total interest, and total cost. The summary section shows the difference as Option 1 minus Option 2. A positive difference means Option 1 is higher for that result. A negative difference means Option 1 is lower.
What to Check Before You Compare Mortgage Options
A side-by-side mortgage comparison is most useful when you understand what the calculator includes and what it leaves out. This tool focuses on principal and interest only. That makes it helpful for comparing the core loan structure, but it is not the same as a full monthly housing cost estimate.
Compare the Same Loan Amount When Possible
If you want to compare only interest rate or term, use the same loan amount for both options. If the loan amounts are different, the results will reflect both the size of the loan and the rate or term differences. That can still be useful, but the comparison answers a broader question.
Look Beyond the Monthly Payment
A longer loan term can lower the monthly payment, but it may increase total interest. A shorter loan term can raise the monthly payment, but it may reduce total interest over the life of the loan. This calculator shows both views so you can compare cash flow and long-term cost.
| Result Shown | What It Means |
|---|---|
| Monthly Payment | Estimated monthly principal and interest payment for that loan option. |
| Total Interest | Estimated interest paid over the full loan term. |
| Total Cost (P+I) | Estimated total of principal plus interest over the full term. |
| Difference | Option 1 result minus Option 2 result. |
Understand the Estimate
The calculator does not include property taxes, homeowners insurance, PMI, closing costs, discount points, escrow payments, or other lender charges. APR may also differ from the stated interest rate because APR can include certain fees. Real mortgage costs can vary by lender rules, credit profile, loan type, fees, and market conditions.
Use the result as a planning estimate, not as financial advice or a loan approval quote. For an actual mortgage offer, review the lender’s payment breakdown and loan documents carefully.
Frequently Asked Questions
What is a mortgage comparison calculator?
A mortgage comparison calculator estimates how two fixed-rate mortgages compare. This calculator uses loan amount, annual interest rate, and loan term for each option. It shows monthly payment, total interest, total principal-plus-interest cost, and the difference between the two loan options.
How do I compare two mortgage loans?
To compare two mortgage loans, enter the loan amount, annual interest rate, and loan term for each option. The calculator then shows both monthly payments and total costs side by side. Use the difference rows to see whether Option 1 is higher or lower than Option 2.
Does this calculator include taxes and insurance?
No, this calculator does not include property taxes or homeowners insurance. It also does not include PMI, closing costs, escrow payments, or lender fees. The results isolate principal and interest so you can compare the loan payment formula without other housing costs mixed in.
Why is the lower monthly payment not always cheaper?
The lower monthly payment is not always cheaper because a longer loan term can create more total interest. This calculator shows monthly payment and total interest separately. That helps you see whether a lower payment comes with a higher long-term principal-plus-interest cost.
What does total cost P+I mean?
Total cost P+I means the total estimated principal and interest paid over the full loan term. The calculator finds it by multiplying the monthly payment by the number of monthly payments. It does not include taxes, insurance, PMI, closing costs, or other fees.
How accurate is this mortgage comparison calculator?
This mortgage comparison calculator is accurate to the fixed-rate principal-and-interest formula used in the code. Actual loan costs may differ because lenders may include fees, APR adjustments, insurance, taxes, PMI, escrow rules, and closing costs that this calculator does not include.
Can this calculator compare a 15-year and 30-year mortgage?
Yes, this calculator can compare different loan terms, including 15-year and 30-year mortgages. Enter one term for Loan Option 1 and another term for Loan Option 2. The calculator will estimate each monthly payment, total interest, and total principal-plus-interest cost.