How is a monthly mortgage payment calculated?

Monthly P&I is calculated using the formula: M = P × r(1+r)^n / ((1+r)^n − 1), where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. For example, a $320,000 loan at 7% for 30 years gives a monthly payment of approximately $2,129 in principal and interest. Over 30 years, total interest paid would be roughly $446,000 — more than the original loan.

What is included in a monthly mortgage payment?

A full mortgage payment typically has four components, often called PITI: Principal, Interest, Taxes, and Insurance. This calculator shows P&I only — the loan repayment portion. Escrow for property taxes (typically 1–2% of home value per year) and homeowners insurance (typically $1,200–$2,000/year) add roughly $200–$600/month to your actual payment, depending on your location and home value.

How much does a 1% difference in interest rate cost?

On a $400,000 loan with a 30-year term, the difference between a 6% and 7% rate is approximately $239 per month — that is about $86,000 more in total interest at the higher rate. Even a 0.5% rate difference on a $400,000 loan adds roughly $43,000 in total interest over 30 years. Improving your credit score or buying discount points can meaningfully reduce your rate.

What is PMI and when is it required?

Private Mortgage Insurance (PMI) is required by most conventional lenders when your down payment is below 20% of the home price. PMI costs approximately 0.5–1% of the loan amount annually — on a $300,000 loan, that is roughly $125–$250 per month added to your payment. PMI is cancelable once your equity reaches 20% (by law, lenders must cancel it at 22% equity automatically). FHA loans have their own mortgage insurance that may last the life of the loan.

What are mortgage points and should I buy them?

Mortgage points (discount points) are prepaid interest you pay at closing to permanently lower your interest rate. Each point costs 1% of the loan amount and typically reduces the rate by 0.25%. On a $400,000 loan, one point costs $4,000 and drops the rate from 7.0% to 6.75%, saving about $66/month. Break-even: $4,000 ÷ $66 = 60 months (5 years). If you plan to stay in the home more than 5 years and have cash to spare, buying points can be cost-effective. Refinancing before break-even makes points a sunk cost.

When does PMI go away?

PMI (private mortgage insurance) on a conventional loan must be canceled by your lender automatically once your loan balance reaches 78% of the original home value (22% equity) — this is mandated by the Homeowners Protection Act. You can also request cancellation at 80% LTV by submitting a written request. If your home has appreciated, you can request a new appraisal to establish the higher value and reach 20% equity sooner. FHA loans with less than 10% down have MIP (mortgage insurance premium) for the life of the loan; refinancing to conventional is the only way to eliminate it.

What is the difference between a fixed-rate and adjustable-rate mortgage?

A fixed-rate mortgage (30-year or 15-year) locks in your interest rate for the full loan term — your principal and interest payment never changes. An adjustable-rate mortgage (ARM, e.g., 5/1 ARM) has a fixed rate for an initial period (5 years in this example), then adjusts annually based on a benchmark index (usually SOFR) plus a margin. ARMs start with a lower rate than fixed mortgages but carry rate risk after the initial period. They make sense if you plan to sell or refinance before the adjustment period begins.

Mortgage Calculator — Monthly Payment & Amortization

Calculates monthly mortgage payment, total interest, and yearly amortization for any home loan amount, rate, and term.

Year	Interest	Principal	Balance
1	$22,297.02	$3,250.59	$316,749.41
2	$22,062.04	$3,485.58	$313,263.83
3	$21,810.07	$3,737.55	$309,526.28
4	$21,539.88	$4,007.74	$305,518.54
5	$21,250.16	$4,297.46	$301,221.09
6	$20,939.50	$4,608.12	$296,612.97
7	$20,606.37	$4,941.24	$291,671.73
8	$20,249.17	$5,298.44	$286,373.28
9	$19,866.15	$5,681.47	$280,691.81
10	$19,455.43	$6,092.18	$274,599.63
11	$19,015.03	$6,532.59	$268,067.04
12	$18,542.79	$7,004.83	$261,062.21
13	$18,036.41	$7,511.21	$253,551.00
14	$17,493.42	$8,054.20	$245,496.81
15	$16,911.18	$8,636.43	$236,860.37
16	$16,286.85	$9,260.76	$227,599.61
17	$15,617.39	$9,930.22	$217,669.39
18	$14,899.54	$10,648.08	$207,021.31
19	$14,129.79	$11,417.83	$195,603.48
20	$13,304.39	$12,243.23	$183,360.25
21	$12,419.33	$13,128.29	$170,231.96
22	$11,470.28	$14,077.34	$156,154.63
23	$10,452.63	$15,094.99	$141,059.64
24	$9,361.41	$16,186.20	$124,873.43
25	$8,191.31	$17,356.31	$107,517.13
26	$6,936.62	$18,611.00	$88,906.13
27	$5,591.23	$19,956.39	$68,949.75
28	$4,148.58	$21,399.03	$47,550.71
29	$2,601.64	$22,945.97	$24,604.74
30	$942.88	$24,604.74	$0.00

How to Use This Mortgage Calculator

This mortgage calculator estimates your monthly payment, total interest, and full amortization schedule for any home loan. Enter your home price, down payment, interest rate, and loan term to get an instant estimate of your monthly principal and interest payment. Select your loan term using the 15 / 20 / 25 / 30 year buttons — results update in real time as you type. The calculator also shows total interest paid, total cost of the loan, estimated payoff date, and a full year-by-year amortization schedule below the result cards.

This calculator computes principal and interest (P&I) only. Your actual monthly mortgage payment will also include property taxes, homeowners insurance, and possibly PMI — factors that vary by location and loan. Use P&I as the baseline and add those estimates on top when budgeting.

How Monthly Mortgage Payments Are Calculated

The standard mortgage payment formula 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 payments (years × 12). This formula produces a fixed payment that stays constant throughout the loan term — early payments are mostly interest, while later payments shift toward principal.

For example: a $320,000 loan at 7% for 30 years produces a monthly payment of approximately $2,129. Of the first payment, roughly $1,867 goes to interest and only $262 to principal. By year 20, those proportions begin to flip significantly. This is why extra early payments are so powerful — they reduce the principal base that all future interest is calculated on.

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Understanding Your Amortization Schedule

The amortization table below the results shows a yearly summary of your loan — annual interest paid, annual principal paid, and remaining balance at the end of each year. In the early years of a 30-year mortgage, as much as 85–90% of each payment goes toward interest. By year 15, the split is typically around 55% interest and 45% principal. In the final years, nearly all of each payment goes to principal.

Use the amortization schedule to understand how much equity you are building each year. Equity is the difference between your home's value and the remaining loan balance. Reaching 20% equity (remaining balance drops to 80% of original home price) is when PMI becomes cancelable on conventional loans.

How Interest Rate Affects Your Payment

Interest rate has a significant impact on both monthly payment and total cost. On a $400,000 30-year loan: at 6%, the monthly P&I is approximately $2,398 and total interest is ~$463,000. At 7%, those figures rise to ~$2,661/month and ~$558,000 total interest — a difference of $263/month and $95,000 over the life of the loan. A single percentage point change is not trivial.

Factors that affect your mortgage rate include credit score (760+ typically gets the best rates), loan-to-value ratio (lower LTV = lower rate), loan type (conventional vs. FHA vs. VA), and market conditions (the 10-year Treasury yield is a key benchmark). Shopping three or more lenders typically yields rate differences of 0.25–0.75%, which translates to thousands in savings over 30 years.

15-Year vs. 30-Year Mortgage

The choice between a 15-year and 30-year mortgage is one of the most impactful financial decisions in homeownership. On a $320,000 loan at 7%: the 30-year payment is approximately $2,129/month with $446,000 in total interest; the 15-year payment is approximately $2,876/month with only $197,000 in total interest — a savings of $249,000. However, the 15-year payment is about 35% higher.

If you can comfortably afford the 15-year payment, it is almost always the mathematically superior choice. If the payment is tight, the 30-year with regular extra payments offers a middle ground — you get the payment flexibility of a 30-year but can pay it off faster and save significantly on interest. Use the mortgage recast calculator to model the impact of lump-sum principal payments on a 30-year loan.

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What Is PMI and When Does It Apply?

Private Mortgage Insurance (PMI) is required on conventional loans when the borrower puts down less than 20% of the home price. It protects the lender, not the borrower, in case of default. PMI is not a permanent cost — it can be cancelled once your loan-to-value ratio drops to 80% (20% equity), either through payments or home appreciation. By law, lenders must automatically cancel PMI at 78% LTV.

PMI costs vary by lender, down payment, and credit score, but typically run 0.5–1% of the loan amount annually. On a $320,000 loan, that is $133–$267 per month added to your P&I. When budgeting for a home with less than 20% down, always factor PMI into your total monthly cost until equity milestones are reached.

Types of Mortgages: Fixed, ARM, FHA, VA, and Jumbo

Not all mortgages are the same. 30-year and 15-year fixed-rate mortgages are the most common — identical monthly payments for the full term provide predictability. Adjustable-rate mortgages (ARMs) offer a lower initial rate (typically 0.5–1.5% below a 30-year fixed) for 3, 5, 7, or 10 years before adjusting annually. They are appropriate for borrowers who plan to sell or refinance before the adjustment period.

FHA loans allow 3.5% down with a 580+ credit score, making homeownership accessible to first-time buyers with limited savings, but require MIP (mortgage insurance premium) for the life of the loan if down payment is under 10%. VA loans are available to eligible veterans and active military with no down payment required and no PMI. Jumbo loans exceed conforming loan limits ($766,550 in most areas in 2024) and typically require 10–20% down and stronger credit. Use this calculator to compare monthly payments across all scenarios.

Mortgage Tips for First-Time Buyers

First-time buyers often underestimate the full cost of homeownership. Beyond principal, interest, taxes, and insurance, budget for maintenance (typically 1–2% of home value per year), HOA fees if applicable, and closing costs (2–5% of home price, due at closing). Our closing cost calculator can help estimate what you will owe at the closing table.

Check your credit score first. A 760+ score qualifies for the best rates — improving from 700 to 760 can lower your rate by 0.25–0.5%.
Get pre-approved before house hunting. Pre-approval shows sellers you are serious and locks in your rate for 60–90 days.
Compare loan types. FHA loans allow 3.5% down with a 580 credit score; conventional loans with 5–20% down may be cheaper long-term for buyers with good credit.
Don't max out your approval. Lenders may approve you for more than you should borrow. A common rule: keep housing costs under 28% of gross monthly income (the “front-end ratio”).
Use a rent affordability calculator to compare renting vs. buying before committing — the break-even timeline is often 4–7 years.

Financial Disclaimer

This calculator is for educational and planning purposes only. Results are estimates based on a standard amortization formula. Actual mortgage payments will include property taxes, homeowners insurance, and possibly PMI, which are not included here. Interest rates, fees, and terms vary by lender, credit score, loan type, and market conditions. This tool does not constitute financial, mortgage, or legal advice. Consult a licensed mortgage professional for guidance specific to your situation.

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