Mortgage Calculator
Calculate your monthly mortgage payment, total interest paid over the life of the loan, and view a year-by-year amortization schedule. Enter your home price, down payment, interest rate, and loan term to get started.
Last updated: April 8, 2026· Reviewed by the CalcNeeds Team
About This Calculator
This mortgage calculatortells you the monthly principal-and-interest payment for any home loan, the total interest you'll pay over the life of the mortgage, and the full year-by-year amortization schedule. Enter the home price, your down payment, the interest rate, and the loan term — the math updates instantly. Whether you're shopping for a 15-year fixed, a standard 30-year, or a jumbo loan, the formula is the same and the answer is below.
Mortgage payments are the single biggest line item in most household budgets, and small differences in rate or term translate to tens of thousands of dollars over the life of the loan. Use this calculator to compare scenarios side by side before you commit to an offer.
How a mortgage payment is calculated
The standard amortization formula is M = P × [r(1+r)^n] / [(1+r)^n − 1], where:
M is your monthly principal-and-interest payment, P is the loan principal (home price minus down payment), r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments (years × 12).
Plug in $400,000 at 6.5% for 30 years and you get: P = 400,000, r = 0.0054, n = 360. M ≈ $2,528. Over 30 years you'd pay about $510,000 in interest on top of the $400,000 principal — nearly $910,000 total.
Each monthly payment is split between interest (calculated on the remaining balance) and principal (the part that actually reduces what you owe). Early in the loan, almost all of the payment goes to interest. By year 20, the split flips and most of each payment is going to principal. The amortization schedule above shows the year-by-year breakdown.
PITI: principal, interest, taxes, and insurance
This calculator computes the P&I portion of your payment. Lenders refer to your full housing payment as PITI — Principal, Interest, Taxes, and Insurance. Your actual monthly housing cost will be the P&I shown above plus:
Property tax:typically 0.5%–2.5% of home value per year, depending on your state and county. On a $400,000 home at 1.5%, that's $500/month.
Homeowners insurance: usually $100–$300/month depending on coverage, region, and risk factors.
PMI (private mortgage insurance):required if your down payment is less than 20%. Typically 0.3%–1.5% of loan value per year. On a $400,000 loan that's $100–$500/month, dropping off once you reach 20% equity.
HOA dues, if applicable, get added on top.
As a rule of thumb, add roughly $700–$1,200 to the calculated P&I to get a realistic full housing payment.
15-year vs. 30-year mortgages
The two most common mortgage terms in the U.S. are 15 and 30 years. The trade-off is straightforward:
30-year:lower monthly payment, much higher total interest. On a $400,000 loan at 6.5%: ~$2,528/month, ~$510,000 in interest over the loan's life.
15-year: higher monthly payment, dramatically less interest. Same loan at 6.0% (15-year rates are usually ~0.5% lower): ~$3,375/month, ~$208,000 in interest.
The 15-year saves roughly $300,000 in interest, but the monthly payment is ~$850 higher. If you can afford the payment, the 15-year is mathematically the better deal. If cash flow flexibility matters more — or if you can invest the difference at a higher return than the mortgage rate — the 30-year may make sense.
How much house can you afford?
The most common rule of thumb is the 28/36 rule: spend no more than 28% of your gross monthly income on housing (PITI), and no more than 36% on total debt payments (housing + car + student loans + credit cards).
At a $100,000 annual gross income, that's ~$8,333/month → max housing payment of ~$2,333. Working backward through the amortization formula at 6.5% for 30 years, that supports a total loan of about $370,000, or a home around $460,000 with a 20% down payment.
Lenders may approve you for more than the 28/36 rule suggests. Resist the urge to max out — leaving headroom in your budget is what makes home ownership comfortable instead of stressful.
APR vs. interest rate
The interest rate is the cost of borrowing the principal, expressed as a percentage. The APR (Annual Percentage Rate) is the interest rate plus most lender fees and closing costs, also expressed as a percentage. APR is always equal to or higher than the rate.
When comparing offers from different lenders, compare APRs — not rates. A low rate with high origination fees can have a worse APR (and worse total cost) than a slightly higher rate with no fees.
Frequently Asked Questions
How is a mortgage payment calculated?
Use the 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 total number of monthly payments. The calculator above does this automatically. The result is your monthly principal-and-interest portion; add property tax, insurance, and PMI for the full housing payment.
How much house can I afford on $100,000 a year?
Using the 28% housing rule, your max monthly housing payment is about $2,333. At a 6.5% rate over 30 years, that supports a loan of roughly $370,000, or a home around $460,000 with a 20% down payment. Adjust based on your other debts, savings, and how much cushion you want in your budget.
What's the difference between APR and interest rate?
The interest rate is the cost of borrowing the principal, expressed as a yearly percentage. APR includes that rate plus most lender fees and closing costs, so it reflects the true total cost of the loan. APR is always equal to or higher than the rate. Compare APRs across lenders to make an apples-to-apples comparison.
Should I get a 15-year or 30-year mortgage?
A 15-year mortgage saves you a huge amount in total interest (often $200K+ on a typical loan) but has a much higher monthly payment. A 30-year mortgage offers lower monthly payments and more flexibility, at the cost of paying significantly more interest overall. If you can comfortably afford the 15-year payment, it's the better mathematical choice. If cash-flow flexibility matters or you want to invest the difference, a 30-year is reasonable.
What is PMI and when does it go away?
PMI (Private Mortgage Insurance) is required by lenders when your down payment is less than 20% of the home's value. It typically costs 0.3%–1.5% of the loan amount per year. Federal law requires lenders to automatically cancel PMI when you reach 22% equity in the home (based on the original purchase price). You can also request cancellation at 20% equity. Refinancing or making extra principal payments to reach 20% faster can save thousands.
How much should I put down on a house?
20% is the traditional benchmark — it lets you avoid PMI and gets you better loan terms. But it's not required. Conventional loans accept as little as 3% down, FHA loans 3.5%, and VA loans 0% for eligible veterans. Lower down payments mean higher monthly payments, more interest paid, and PMI until you reach 20% equity.
Does this calculator include property taxes and insurance?
No — it calculates the principal-and-interest (P&I) portion only. Add property tax (typically 0.5%–2.5% of home value per year), homeowners insurance ($100–$300/month), and PMI if your down payment is under 20% to get your full PITI payment. As a rule of thumb, add $700–$1,200/month to the P&I figure for a realistic full housing cost.
How much interest will I pay over 30 years?
On a $400,000 loan at 6.5% for 30 years, total interest is approximately $510,000 — more than the loan principal itself. Higher rates and longer terms dramatically increase total interest. Use the amortization schedule above to see exactly how interest accumulates year by year for your specific loan.
Can I pay off my mortgage early?
Yes, and it can save substantial interest. Most modern U.S. mortgages have no prepayment penalty — check your loan documents to confirm. Even small extra payments toward principal reduce the loan term and save interest. An extra $200/month on a $400,000 30-year mortgage at 6.5% can shave roughly 6 years off the loan and save about $130,000 in interest.
About CalcNeeds— We build free, accurate, and easy-to-use calculators for everyday decisions. Our tools are reviewed for accuracy and updated regularly. Have feedback? Let us know.