Mortgage Repayment Calculator
Calculate your estimated monthly mortgage payments, including principal and interest.
Repayment Timeline
Year-by-year summary of your loan repayment journey with extra payments applied.
| Year | Principal Paid | Interest Paid | Remaining Balance |
|---|---|---|---|
| 1 Year 1 | $3,353 | $19,401 | $296,647 |
| 2 Year 2 | $6,931 | $38,578 | $293,069 |
| 3 Year 3 | $10,748 | $57,515 | $289,252 |
| 4 Year 4 | $14,821 | $76,197 | $285,179 |
| 5 Year 5 | $19,167 | $94,605 | $280,833 |
| 6 Year 6 | $23,804 | $112,723 | $276,196 |
| 7 Year 7 | $28,751 | $130,530 | $271,249 |
| 8 Year 8 | $34,030 | $148,006 | $265,970 |
| 9 Year 9 | $39,662 | $165,128 | $260,338 |
| 10 Year 10 | $45,672 | $181,873 | $254,328 |
| 11 Year 11 | $52,084 | $198,215 | $247,916 |
| 12 Year 12 | $58,925 | $214,129 | $241,075 |
| 13 Year 13 | $66,224 | $229,584 | $233,776 |
| 14 Year 14 | $74,013 | $244,550 | $225,987 |
| 15 Year 15 | $82,323 | $258,994 | $217,677 |
| 16 Year 16 | $91,189 | $272,882 | $208,811 |
| 17 Year 17 | $100,649 | $286,176 | $199,351 |
| 18 Year 18 | $110,743 | $298,837 | $189,257 |
| 19 Year 19 | $121,513 | $310,822 | $178,487 |
| 20 Year 20 | $133,004 | $322,085 | $166,996 |
| 21 Year 21 | $145,265 | $332,579 | $154,735 |
| 22 Year 22 | $158,347 | $342,251 | $141,653 |
| 23 Year 23 | $172,305 | $351,048 | $127,695 |
| 24 Year 24 | $187,197 | $358,909 | $112,803 |
| 25 Year 25 | $203,088 | $365,774 | $96,912 |
| 26 Year 26 | $220,042 | $371,574 | $79,958 |
| 27 Year 27 | $238,132 | $376,238 | $61,868 |
| 28 Year 28 | $257,433 | $379,692 | $42,567 |
| 29 Year 29 | $278,027 | $381,852 | $21,973 |
| 30 Year 30 | $300,000 | $382,633 | $0 |
How Your Mortgage Payment Is Calculated
A standard mortgage payment consists of two core components—Principal and Interest—together abbreviated as P&I. Your actual monthly housing cost also includes property taxes and homeowners insurance (together: PITI), and Private Mortgage Insurance if your down payment was under 20%.
The Amortization Formula: > Monthly Payment = P × [r(1+r)^n] / [(1+r)^n − 1]
Where P = loan principal, r = monthly interest rate (annual ÷ 12), n = number of payments.
A $300,000 loan at 7% for 30 years: monthly P&I = $1,996
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📊 How Amortization Shifts Over Time
Early mortgage payments are interest-heavy. This gradually shifts as your balance decreases:
| Year | Monthly Interest | Monthly Principal | Remaining Balance | |---|---|---|---| | 1 | $1,747 | $249 | $297,010 | | 5 | $1,668 | $328 | $283,760 | | 10 | $1,544 | $452 | $263,880 | | 15 | $1,379 | $617 | $237,200 | | 20 | $1,158 | $838 | $200,470 | | 25 | $856 | $1,140 | $148,880 | | 30 | $14 | $1,982 | $0 |
*Example: $300,000 loan at 7%, 30-year term*
Over 30 years you pay: $1,996 × 360 = $718,560** total—meaning **$418,560 in interest on a $300,000 loan.
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⚖️ 15-Year vs 30-Year Mortgage: The True Cost
| | 15-Year Mortgage | 30-Year Mortgage | |---|---|---| | Loan Amount | $300,000 | $300,000 | | Rate (typical 2026) | 6.25% | 7.00% | | Monthly P&I | $2,572 | $1,996 | | Total Paid | $462,960 | $718,560 | | Total Interest | $162,960** | **$418,560 | | Interest Savings | — | $255,600 more | | Monthly Difference | +$576 more | — |
The 15-year saves $255,600 but requires $576/month more. At $576/month invested in a 7% index fund for 30 years, you'd accumulate ~$700,000—roughly equal to the interest savings. The choice depends on discipline and cash flow flexibility.
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💰 Complete Monthly Housing Cost Breakdown
Your lender-required P&I is only part of your actual housing expense:
| Component | Typical Range | |---|---| | Principal & Interest | Calculated from loan terms | | Property Tax (escrowed) | $200–$1,500/month (varies enormously by state) | | Homeowners Insurance | $100–$300/month | | PMI (if <20% down) | $100–$400/month | | HOA Fees (if applicable) | $0–$1,000+/month | | Total PITI + PMI | Often $400–$2,000+ above P&I |
Budget for the full PITI amount, not just P&I, when evaluating affordability.
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📈 Impact of Rate Differences on $300,000 Loan (30 Years)
| Interest Rate | Monthly P&I | Total Interest Paid | |---|---|---| | 5.5% | $1,703 | $313,080 | | 6.0% | $1,799 | $347,640 | | 6.5% | $1,896 | $382,560 | | 7.0% | $1,996 | $418,560 | | 7.5% | $2,097 | $455,040 | | 8.0% | $2,201 | $492,360 |
A 0.5% rate difference on a $300,000 loan = approximately $35,000–$36,000 over 30 years. This is why shopping multiple lenders and comparing APRs (not just rates) is worth several hours of effort.
Frequently Asked Questions
Q: How is a mortgage monthly payment calculated?
A: Monthly payment = Loan Amount × [r(1+r)^n] / [(1+r)^n − 1], where r = monthly rate (annual rate ÷ 12) and n = number of payments. For a $300,000 loan at 7% for 30 years: r = 0.07/12 = 0.005833, n = 360, monthly P&I = $1,996. This only covers principal and interest—add property tax, homeowners insurance, and PMI (if applicable) for your full monthly housing cost.
Q: What is the difference between a 15-year and 30-year mortgage?
A: A 15-year mortgage has higher monthly payments (roughly 30–40% more) but you pay far less total interest—often $200,000–$300,000 less on a $300,000 loan. 30-year mortgages offer lower monthly payments and more cash flow flexibility but dramatically higher total interest cost. 15-year loans also typically carry lower interest rates (0.5–0.75% less) from lenders. The right choice depends on your income stability and whether the monthly savings from a 30-year loan would be invested consistently.
Q: Does my monthly mortgage payment cover taxes and insurance?
A: Standard mortgage calculations show only Principal & Interest (P&I). However, most lenders require an escrow account that collects property taxes and homeowners insurance alongside P&I. These are added to your monthly payment to form the full PITI amount. Property taxes vary significantly by state (from under 0.5% to over 2% of home value annually). Always calculate your full PITI when budgeting for homeownership.
Q: How much of my early mortgage payments go to interest?
A: On a 30-year $300,000 mortgage at 7%, roughly 87% of your first payment goes to interest and only 13% reduces your principal. This gradually shifts over time—by year 15, it's roughly 70% interest / 30% principal, and by year 25, the split has reversed. This front-loading of interest is why extra principal payments made in the early years have such disproportionately large impact on total interest paid.
Example Scenarios
Helped me decide between 15 and 30-year terms. The interest savings on a 15-year loan are eye-opening!
The amortization explanation is great. It is scary how much interest you pay in the first few years.
Simple, fast, and gives me exactly what I need for my budget planning.
Official Sources & Authority References
Important Disclaimer
This calculator provides estimates for informational purposes only and does not constitute tax, legal, or financial advice. Tax laws change annually — verify figures with HMRC or IRS guidance, or consult a qualified tax professional before making financial decisions.
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