Mortgage Calculator
Calculate your monthly payment, total interest paid, and see a full amortization schedule. All calculations run in your browser.
Enter your loan details and click Calculate
Calculate your monthly payment, total interest paid, and see a full amortization schedule. All calculations run in your browser.
Buying a home is likely the largest financial commitment most people will make in their lifetime, and understanding the true cost of a mortgage before signing anything is essential. The Mortgage Calculator on Digital.Finance helps you break down monthly payments, total interest paid, and the full cost of borrowing so you can approach lenders and listings with a clear picture of what you can actually afford. Whether you are a first-time buyer trying to set a realistic budget or an existing homeowner considering a refinance, this tool gives you the numbers you need to make an informed decision.
A mortgage payment has four core components, often abbreviated as PITI: principal, interest, taxes, and insurance. The calculator focuses on principal and interest, which together form the base monthly payment determined by three variables: the loan amount, the annual interest rate, and the loan term. The standard formula used is M = P[r(1+r)^n] / [(1+r)^n - 1], where M is the monthly payment, P is the principal loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of payments. For example, a $300,000 mortgage at 6.5% over 30 years produces a monthly payment of approximately $1,896. Over the full term, you would pay roughly $382,560 in interest alone — more than the original loan itself.
The interest rate structure you choose fundamentally changes the risk profile of your loan. A fixed-rate mortgage locks in the same interest rate for the entire term, so your principal and interest payment never changes. This predictability makes budgeting straightforward and protects you if market rates rise significantly. A 30-year fixed is the most common choice in the United States, though 15-year fixed loans are popular among borrowers who want to build equity faster and pay substantially less interest overall. A $300,000 loan at 6.5% over 15 years carries a higher monthly payment of about $2,613, but the total interest paid drops to roughly $170,000 — a savings of over $210,000 compared to the 30-year option. An adjustable-rate mortgage, or ARM, typically offers a lower introductory rate fixed for an initial period — commonly 5, 7, or 10 years — after which the rate adjusts periodically based on a benchmark index plus a margin. ARMs can be advantageous if you plan to sell or refinance before the adjustment period begins, but they carry the risk of significantly higher payments if rates rise.
Your down payment directly affects both your loan amount and whether you will owe private mortgage insurance, commonly known as PMI. Conventional lenders typically require PMI when the borrower puts down less than 20% of the purchase price. PMI usually costs between 0.5% and 1.5% of the loan amount annually, added to your monthly payment. On a $300,000 home with a 10% down payment, PMI might add $112 to $337 per month until your equity reaches 20%. Putting down 20% eliminates this cost entirely and immediately reduces your principal. FHA loans, which require as little as 3.5% down, carry their own mortgage insurance premiums that often persist for the life of the loan regardless of equity. Running the numbers with different down payment amounts in the calculator can reveal how a larger upfront investment translates into meaningful long-term savings.
Mortgages are amortized loans, meaning each payment covers accrued interest first, with the remainder applied to principal. In the early years of a 30-year mortgage, the vast majority of each payment goes toward interest. On the $300,000 example at 6.5%, your very first payment of $1,896 allocates roughly $1,625 to interest and only $271 to principal. By year 15, that split begins to shift more meaningfully. Understanding amortization helps explain why making even one extra principal payment per year can shave years off your loan term and save tens of thousands of dollars in interest. Many borrowers find that paying one additional monthly payment per year reduces a 30-year mortgage to roughly 25 years.
Refinancing replaces your existing mortgage with a new loan, typically to secure a lower interest rate, change the loan term, or access home equity. The break-even point is the key metric: divide the total closing costs of the refinance by the monthly savings to determine how many months it takes to recoup the upfront expense. If closing costs are $4,000 and your new payment saves you $200 per month, the break-even point is 20 months. Refinancing generally makes sense if you plan to stay in the home beyond that point. Keep in mind that resetting to a new 30-year term, even at a lower rate, can increase total lifetime interest paid if you are already several years into your original loan.
Most conventional loans require a minimum credit score of 620, though scores above 740 typically unlock the best interest rates. FHA loans allow scores as low as 580 with a 3.5% down payment, or as low as 500 with 10% down. The difference between a 680 and a 760 score can easily translate to a 0.5% difference in rate, which on a $300,000 loan over 30 years equals roughly $30,000 in additional interest.
A common guideline is the 28/36 rule: your housing costs should not exceed 28% of your gross monthly income, and your total debt obligations should not exceed 36%. If you earn $7,000 per month before taxes, your maximum housing payment under this rule would be $1,960, and your total monthly debts including housing should stay below $2,520. Lenders also calculate your debt-to-income ratio, or DTI, which most conventional programs cap at 43% to 45%.
Closing costs typically range from 2% to 5% of the loan amount and include lender origination fees, appraisal fees, title insurance, attorney fees (in some states), prepaid property taxes and homeowner's insurance, and recording fees. On a $300,000 loan, expect to pay between $6,000 and $15,000 at closing. Some lenders offer no-closing-cost mortgages, which roll these expenses into a slightly higher interest rate instead of requiring cash upfront.
The right choice depends on your cash flow and financial priorities. A 15-year mortgage builds equity faster and saves a substantial amount in interest, but the higher monthly payment leaves less room for other financial goals like retirement contributions or emergency savings. A 30-year mortgage offers a lower required payment with the flexibility to pay extra toward principal when cash flow allows. Many financial planners suggest choosing a 30-year mortgage and making additional principal payments rather than committing to the higher required payment of a 15-year loan.