Loan Calculator - Monthly Payment & Interest
Calculate monthly payments, total interest, and payoff time for any loan type — mortgages, auto loans, personal loans, and business financing.
Enter your loan amount, interest rate, and term, then add an optional down payment or extra monthly payment to see how much you'll pay and how fast you'll be debt-free.
Loan Calculator - Monthly Payment & Interest
Calculate monthly payments, total interest, and payoff time for any loan type — mortgages, auto loans, personal loans, and business financing.
About the loan calculator
A loan calculator turns a few simple inputs — how much you borrow, the interest rate, and how long you take to repay — into the numbers that actually matter: your monthly payment, the total interest you'll hand the lender, and the grand total you'll repay over the life of the loan. Whether you're sizing up a 30-year mortgage, a 5-year auto loan, a personal loan for debt consolidation, or business financing for new equipment, the same underlying math applies, and the loan payment calculator makes it instant.
The engine behind the calculator is the standard amortization formula for a fixed-rate, fully-amortizing loan: M = P · r · (1 + r)^n / ((1 + r)^n − 1). Here P is the principal (the loan amount minus any down payment), r is the periodic interest rate (your annual rate divided by 12 for monthly payments), and n is the total number of payments (the term in years multiplied by 12). Each month a portion of your payment covers interest on the outstanding balance and the remainder reduces the principal. Early in the loan most of the payment is interest; later most of it is principal. This shifting split is called amortization.
The results tell three stories. The monthly payment is what you commit to every month and is the figure your budget has to absorb. The total interest is the price of borrowing — on a long mortgage it can rival or exceed the amount borrowed. The total paid is principal plus interest, the true lifetime cost of the loan. Comparing these across different rates and terms is the fastest way to see why a lower rate or a shorter term can save tens of thousands of dollars.
Two optional inputs sharpen the picture. A down payment reduces the principal up front, lowering both the monthly payment and the total interest. An extra monthly payment is applied directly to principal each month, shrinking the balance faster than scheduled; the calculator then re-amortizes the loan to show how many months early you'll be debt-free and how much interest you save. Even a modest extra payment on a long loan can cut years off the term.
Use the loan calculator to compare lender offers, decide between a 15- and 30-year mortgage, test whether rounding up your payment is worth it, or simply understand a quote before you sign. Remember it estimates principal and interest only — real-world payments may also include property taxes, homeowners or PMI insurance, HOA dues, and lender fees, so treat the output as a planning baseline rather than a final closing figure.
Loan calculator examples
Click any example button under the calculator to load these scenarios instantly.
| Scenario | Monthly Payment | Details |
|---|---|---|
| 30-Year Fixed Mortgage | ≈ $1,516.96 / month | $240,000 loan (a $300,000 home with 20% / $60,000 down) at 6.5% over 30 years. Total interest is roughly $306,100 over the full term. |
| Auto Loan | ≈ $370.59 / month | $20,000 loan (a $25,000 car with $5,000 down) at 4.25% over 5 years. A short term and low rate keep total interest near $2,237. |
| Personal Loan with Extra Payment | ≈ $475.25 / month, plus $100 extra | $15,000 at 8.75% over 3 years for debt consolidation. Adding $100 extra each month pays the loan off early and trims the total interest. |
How to use the loan calculator
- Enter the loan amount — the total you want to borrow, before any down payment.
- Enter the annual interest rate as a percentage (for example 5.5 for 5.5%) and the loan term in years.
- Optionally add a down payment to reduce the principal, and an extra monthly payment to pay the loan off faster.
- Click Calculate to see your monthly payment, total interest, and total amount paid.
- Adjust the rate or term and recalculate to compare offers, or click Reset to start over.
Loan calculator FAQ
How is my monthly loan payment calculated?
The calculator uses the standard amortization formula M = P · r · (1 + r)^n / ((1 + r)^n − 1), where P is the principal, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments (years × 12). This produces a fixed payment that fully repays the loan by the end of the term.
Does the calculator include taxes, insurance, and fees?
No. It estimates principal and interest only. Real mortgage payments often also include property taxes, homeowners or PMI insurance, HOA dues, and lender fees. Add those separately to estimate your full monthly housing cost.
How does an extra monthly payment help?
Every extra dollar goes straight to principal, so the balance shrinks faster than scheduled and less interest accrues. The calculator re-amortizes the loan with your extra payment to show how many months early it's paid off and how much interest you save.
What does the down payment field do?
The down payment is subtracted from the loan amount to get the principal you actually finance. A larger down payment lowers both your monthly payment and the total interest you pay over the life of the loan.
Should I choose a shorter or longer loan term?
A shorter term means higher monthly payments but far less total interest, because you're borrowing for less time. A longer term lowers the monthly payment but increases total interest. Use the calculator to compare both and pick what fits your budget.
Is this calculator accurate for any loan type?
Yes, for any fixed-rate, fully-amortizing loan — mortgages, auto loans, personal loans, and most business loans. It is not designed for variable-rate loans, interest-only loans, or credit cards with revolving balances, which follow different repayment rules.