Mortgage Comparison Calculator
Compare mortgage options side by side to see how different rates, terms, and payments affect your total cost.
How the Mortgage Comparison Calculator Works
This calculator lets you compare up to three mortgage loan options side by side. It calculates the monthly payment, total interest paid, and total cost over the full loan term for each option. The comparison is based on standard amortization formulas that assume a fixed interest rate and consistent monthly payments over the life of the loan.
The key inputs for each loan option are:
- Loan Amount – The total amount you plan to borrow, after your down payment.
- Interest Rate – The annual percentage rate (APR) offered by the lender.
- Loan Term – The length of the loan, typically 15 or 30 years.
The calculator does not account for variable-rate loans, taxes, insurance, or private mortgage insurance (PMI). It provides a direct cost comparison based solely on the principal and interest components of a mortgage.
How to Use the Calculator
Enter the loan amount, interest rate, and term for each mortgage option you want to compare. You can compare one, two, or three options at a time. The results update automatically as you adjust the inputs.
To get a meaningful comparison, keep the loan amount consistent across options and vary the rate or term. This isolates the effect of each variable on your monthly payment and total cost.
Understanding the Results
The calculator displays three key metrics for each loan option:
- Monthly Payment – The fixed amount you will pay each month. This is the most immediate factor in your monthly budget.
- Total Interest Paid – The cumulative interest cost over the full loan term. A lower rate or shorter term reduces this number significantly.
- Total Cost – The sum of the loan amount plus total interest. This represents the full financial cost of the loan.
When comparing options, look at the trade-off between monthly payment and total cost. A lower monthly payment often comes with a longer term, which increases total interest. A shorter term or lower rate reduces total cost but may require a higher monthly payment.
Common Mistakes When Comparing Mortgages
Comparing mortgages is straightforward, but a few common errors can lead to misleading conclusions:
- Comparing loans with different amounts – Always use the same loan amount for each option. Differences in total cost should reflect rate and term, not a different principal.
- Ignoring the loan term – A 30-year loan at a low rate may have a lower monthly payment than a 15-year loan at a slightly higher rate, but the total interest will be much higher. Compare both metrics.
- Focusing only on the monthly payment – The monthly payment is important, but the total cost over the life of the loan matters just as much. A lower monthly payment can cost you tens of thousands more in interest.
- Forgetting about other costs – This calculator covers principal and interest only. Closing costs, property taxes, homeowners insurance, and PMI can significantly affect your actual monthly payment and total cost.
Limitations of This Calculator
This calculator is designed for fixed-rate mortgages only. It does not support adjustable-rate mortgages (ARMs), interest-only loans, or balloon payments. The results assume that you make exactly the required monthly payment every month and do not make extra payments.
The calculator also does not include:
- Property taxes
- Homeowners insurance
- Private mortgage insurance (PMI)
- HOA fees
- Closing costs
These costs vary by location, lender, and loan type. For a complete picture of your monthly housing expense, add these costs to the monthly payment shown here.
Practical Use Cases
This calculator is useful in several common scenarios:
- Comparing a 15-year vs. 30-year mortgage – See how much more you pay in interest with a longer term and whether the lower monthly payment is worth the extra cost.
- Evaluating rate offers from different lenders – Enter the same loan amount and term with different rates to see which lender saves you the most money.
- Deciding whether to buy points – If you are considering paying discount points to lower your rate, compare the loan with and without points to see how long it takes to break even.
- Planning a refinance – Compare your current mortgage terms with a new loan to determine if refinancing makes financial sense.
Frequently Asked Questions
What is the difference between interest rate and APR?
The interest rate is the cost of borrowing the principal, expressed as a percentage. APR (Annual Percentage Rate) includes the interest rate plus certain lender fees and closing costs, giving a more complete picture of the loan's cost. This calculator uses the interest rate, not APR.
Should I choose a 15-year or 30-year mortgage?
A 15-year mortgage has higher monthly payments but significantly lower total interest. A 30-year mortgage has lower monthly payments but costs much more in interest over time. The right choice depends on your budget, cash flow, and long-term financial goals. Use this calculator to compare the numbers for your specific situation.
Does the calculator include property taxes and insurance?
No. This calculator only covers principal and interest. Property taxes, homeowners insurance, and PMI are separate costs that vary by location and loan type. You need to add them to the monthly payment shown here for a complete estimate of your monthly housing expense.
Can I use this calculator for an adjustable-rate mortgage (ARM)?
No. This calculator assumes a fixed interest rate for the entire loan term. ARMs have rates that change over time, so the results would not be accurate. For ARMs, you need a calculator that accounts for rate adjustments and caps.
What happens if I make extra payments?
This calculator assumes you make only the required monthly payment. Making extra payments reduces your principal faster, which lowers total interest and shortens the loan term. The results shown here do not reflect the impact of extra payments.