Mortgage Calculator
Calculate monthly mortgage payments and total cost.
How to use Mortgage Calculator
Enter Your Loan Amount
Locate the 'Loan Amount' field at the top of the calculator. Type the total home price or loan amount in dollars (e.g., 350000). The field accepts values from $10,000 to $10,000,000.
Input Your Interest Rate
Click the 'Interest Rate (%)' field below the loan amount. Enter your annual interest rate as a decimal (e.g., 6.5 for 6.5%). Use rates between 2% and 12% for typical mortgages.
Set Your Loan Term
Select the 'Loan Term (Years)' dropdown menu. Choose 15, 20, or 30 years. The most common selection is 30 years for primary mortgages.
View Your Results
Results display automatically below the input fields showing: Monthly Payment (principal + interest), Total Amount Paid over loan term, and Total Interest Paid. All values update in real-time as you adjust inputs.
Adjust and Compare
Modify any field to see instant calculations. Compare scenarios like different interest rates or loan terms side-by-side. No need to reset—simply edit values and results recalculate immediately.
Related Tools
Mortgage calculator: estimate your monthly payment instantly
Mortgage calculator: estimate your monthly payment instantly
Want to know what a home loan will cost you each month? Use ToolHQ's free mortgage calculator to get your monthly payment, total interest, and full amortization breakdown in seconds.
ToolHQ's mortgage calculator is a free browser-based tool that calculates monthly mortgage payments, total interest paid, and a full amortization schedule for any home loan.
Buying a home is one of the biggest financial decisions most people make. Running the numbers before you sign anything gives you negotiating power, helps you compare loan offers, and shows you exactly how much that interest rate difference actually costs over 30 years.
Key Takeaways
- Your monthly payment depends on loan amount, interest rate, and loan term -- not just the home price
- A 1% difference in interest rate on a $400,000 loan changes your total interest paid by over $80,000 over 30 years
- The amortization schedule shows exactly how much of each payment goes to principal vs. interest
- Early in the loan, most of your payment covers interest rather than reducing the balance
- No login required -- enter your loan details and see your full payment breakdown instantly
How mortgage payments are calculated
A mortgage payment has four potential components, often called PITI: Principal, Interest, Taxes, and Insurance. ToolHQ's calculator focuses on the principal and interest portion, which is the fixed, calculable part of your payment.
The formula for a fixed-rate monthly mortgage payment is:
M = P [r(1+r)^n] / [(1+r)^n - 1]
Where P is the loan principal, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments (loan term in years multiplied by 12).
A $350,000 loan at 6.5% over 30 years produces a monthly principal-and-interest payment of $2,212. By the end of the loan, you will have paid $446,320 in interest on top of the $350,000 principal -- more than the original loan amount.
The Consumer Financial Protection Bureau explains that understanding your loan's amortization is critical before choosing between a 15-year and 30-year term. A 15-year term has higher monthly payments but cuts total interest roughly in half. According to the Wikipedia article on mortgages, most residential mortgages in the US are structured as 30-year fixed-rate loans, though 15-year and adjustable-rate options are common alternatives.
When you need a mortgage calculator
Running mortgage numbers isn't just for first-time buyers. You need this tool anytime a home loan is in the picture.
Mini-story: Daniela is a 34-year-old graphic designer in Austin who found a home listed at $425,000. Her lender pre-approved her for a 30-year loan at 7.1% with 10% down. She entered the numbers: loan amount $382,500, rate 7.1%, 30 years. The calculator showed her a monthly payment of $2,567 and total interest of $541,120. She then changed the rate to 6.8% to see what a rate buydown would cost. The monthly payment dropped to $2,506 -- a $61 monthly difference -- but the total interest savings over 30 years were $21,960. She paid the buydown fee of $3,800 and came out ahead after 62 months.
You'll want to run this calculator when:
- Comparing two loan offers with different rates and terms
- Deciding between a 15-year and 30-year mortgage
- Evaluating how a larger down payment affects your payment
- Checking how extra monthly payments would shorten your loan term
- Figuring out your maximum comfortable loan amount before house hunting
Run your mortgage numbers at ToolHQ
How to use the mortgage calculator
- Enter the home price or the loan amount you expect to borrow after your down payment.
- Enter your down payment as a dollar amount or percentage. The tool calculates the loan principal automatically.
- Enter the annual interest rate as a percentage. Use the rate from your lender's quote or a current market estimate.
- Select the loan term -- typically 15 or 30 years.
- View your results. You'll see the monthly payment, total amount paid, total interest paid, and the full amortization table showing each month's payment split.
Tips for reading your mortgage results
The amortization schedule is the most powerful part of the output. In the early years of a 30-year mortgage, the vast majority of each payment goes toward interest, not principal. On a $350,000 loan at 6.5%, month one splits as approximately $213 to principal and $1,896 to interest. By month 300 (year 25), the split flips to around $1,900 to principal and $209 to interest.
This is why extra payments made early in the loan save disproportionately large amounts of interest. Paying an extra $200 per month from month one on that $350,000 loan cuts the loan term by roughly six years and saves over $80,000 in interest.
Mini-story: Marcus, a 41-year-old software engineer, used the mortgage calculator when refinancing his home in 2024. He had 22 years left on his 30-year mortgage and was considering a 15-year refinance. The calculator showed his new payment would be $380 higher per month, but total interest over the remaining life of the loan would be $87,000 less. He compared that to his investment returns and decided the refinance made sense given current rates.
Use ToolHQ's loan calculator for non-mortgage loans like auto or personal finance. If you want to see how lump-sum extra payments grow over time, the compound interest calculator helps compare paydown vs. investment scenarios. Find more financial tools in the ToolHQ calculator category.
Understanding your amortization schedule
The amortization schedule is the most useful output of any mortgage calculator, and most people do not study it closely enough before signing a loan. Here is what it shows and why it matters for your actual financial decisions.
How early payments go mostly to interest. On a $300,000 loan at 7% over 30 years, the monthly payment is $1,996. In month one, only $246 of that goes to reducing the loan balance. The remaining $1,750 goes to interest. That ratio shifts very slowly. By year five (month 60), you are still paying roughly $1,693 in interest and $303 in principal per month. You have made $119,760 in payments but reduced the loan balance by only about $14,000.
The power of extra payments early. Because the interest charge each month is based on the remaining balance, any payment that reduces the balance faster saves a disproportionate amount of interest. On that same $300,000 / 7% / 30-year loan, paying an extra $200 per month from the start reduces the loan term by about 5 years and 4 months and saves approximately $76,000 in total interest. The extra $200 does not go toward interest -- it goes directly to principal reduction, which then lowers the interest charged in every subsequent month.
How to use the amortization data to make decisions.
First, check the break-even point on extra payments. If you plan to sell or refinance in seven years, the interest savings from paying extra come mostly in the future -- not in the first seven years. The amortization schedule shows exactly how much balance you will have at any future point, which tells you the equity you can expect when you sell.
Second, compare loan terms side by side. Run the $300,000 loan at 7% for 30 years (monthly payment: $1,996, total interest: $418,527) and for 15 years (monthly payment: $2,696, total interest: $185,389). The 15-year loan costs $700 more per month but saves $233,138 in interest. The schedule makes that trade-off concrete and visual.
Third, time lump-sum extra payments. When making a one-time extra payment (a bonus, a tax refund), the earlier in the loan you make it, the more it saves. The amortization schedule lets you model the impact of a $5,000 extra payment in year two versus year ten.
Frequently asked questions
Does the calculator include property taxes and insurance?
No. Property taxes and insurance vary widely by location and policy. The calculator shows principal and interest only. Add your estimated monthly taxes and insurance to get your total housing cost.
What interest rate should I enter?
Use the rate from your lender's Loan Estimate document. If you're shopping around, use the current 30-year fixed average from Freddie Mac's weekly survey as a benchmark.
What is the difference between a 15-year and 30-year mortgage?
A 15-year mortgage has higher monthly payments but cuts total interest paid roughly in half and builds equity much faster. A 30-year mortgage has lower payments but costs significantly more in total interest over time.
What is a biweekly payment strategy?
Instead of making one payment per month, you pay half your monthly payment every two weeks. Because there are 52 weeks in a year, you end up making 26 half-payments, the equivalent of 13 full monthly payments instead of 12. That extra payment per year goes entirely to principal reduction. On a 30-year mortgage, a biweekly payment schedule typically shortens the loan by 4 to 6 years and saves tens of thousands of dollars in interest. Check with your lender whether they accept and properly apply biweekly payments before setting one up.
Can I use this for an adjustable-rate mortgage (ARM)?
You can enter the initial fixed rate of an ARM to see your starting payment. Keep in mind the rate and payment will change after the fixed period ends.
How does a larger down payment affect my monthly payment?
A larger down payment reduces the loan principal, which lowers both your monthly payment and your total interest. It also typically eliminates private mortgage insurance (PMI) if you reach 20% down.
The short version
Before you make an offer, before you sign a loan, before you commit to a rate -- run the numbers. ToolHQ's mortgage calculator shows your monthly payment, total interest, and full amortization schedule in seconds with no registration required.
The amortization table is especially useful: it shows you exactly how your money splits between principal and interest every single month for the life of the loan.
For related financial calculations, try ToolHQ's loan calculator for personal and auto loans, or use the compound interest calculator to compare mortgage paydown against investment scenarios.
Calculate your mortgage payment now