Mortgage Calculator
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Amortization schedule by year
| Year | Interest | Principal | Balance |
|---|---|---|---|
| 1 | $23,511.00 | $3,730.12 | $346,269.88 |
| 2 | $23,251.28 | $3,989.84 | $342,280.04 |
| 3 | $22,973.48 | $4,267.64 | $338,012.40 |
| 4 | $22,676.33 | $4,564.79 | $333,447.61 |
| 5 | $22,358.49 | $4,882.63 | $328,564.98 |
| 6 | $22,018.53 | $5,222.59 | $323,342.39 |
| 7 | $21,654.89 | $5,586.23 | $317,756.16 |
| 8 | $21,265.93 | $5,975.19 | $311,780.97 |
| 9 | $20,849.89 | $6,391.23 | $305,389.74 |
| 10 | $20,404.88 | $6,836.24 | $298,553.50 |
| 11 | $19,928.89 | $7,312.23 | $291,241.26 |
| 12 | $19,419.75 | $7,821.37 | $283,419.90 |
| 13 | $18,875.17 | $8,365.95 | $275,053.94 |
| 14 | $18,292.66 | $8,948.46 | $266,105.49 |
| 15 | $17,669.60 | $9,571.52 | $256,533.97 |
| 16 | $17,003.15 | $10,237.97 | $246,296.00 |
| 17 | $16,290.31 | $10,950.81 | $235,345.19 |
| 18 | $15,527.82 | $11,713.30 | $223,631.89 |
| 19 | $14,712.25 | $12,528.87 | $211,103.02 |
| 20 | $13,839.89 | $13,401.23 | $197,701.79 |
| 21 | $12,906.79 | $14,334.33 | $183,367.47 |
| 22 | $11,908.72 | $15,332.40 | $168,035.07 |
| 23 | $10,841.16 | $16,399.96 | $151,635.11 |
| 24 | $9,699.26 | $17,541.86 | $134,093.25 |
| 25 | $8,477.86 | $18,763.26 | $115,329.99 |
| 26 | $7,171.41 | $20,069.71 | $95,260.28 |
| 27 | $5,774.00 | $21,467.12 | $73,793.17 |
| 28 | $4,279.29 | $22,961.83 | $50,831.33 |
| 29 | $2,680.51 | $24,560.62 | $26,270.72 |
| 30 | $970.40 | $26,270.72 | $0.00 |
A mortgage calculator estimates the monthly principal-and-interest payment on a home loan, plus total interest over the life of the loan and a full amortization schedule. Enter your loan amount, interest rate, and term — the calculator updates instantly as you type.
The "extra monthly payment" field shows the most under-appreciated lever in personal finance: even $100 per month extra on a 30-year mortgage typically cuts the loan by 4–5 years and saves tens of thousands in interest.
Key takeaway
At the start of the loan, almost every dollar of your payment is interest. Each extra principal dollar permanently removes all the future interest that dollar would have generated — which is why early extra payments are so disproportionately powerful. A mortgage isn't really one big loan; it's a series of compounding interest charges on a shrinking balance, and you control how fast that balance shrinks.
How it's calculated
The standard fixed-rate mortgage formula 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 ÷ 12 ÷ 100)
- n is the number of monthly payments (years × 12)
The amortization schedule shows how each payment splits between interest and principal. Early in the loan, most of the payment goes to interest; later, it flips and most goes to principal. Extra payments accelerate that flip — every extra dollar goes straight to principal, eliminating all the future interest that dollar would have generated.
Source: Standard fixed-rate mortgage amortization formula
Quick tricks
- Monthly P&I per $100K of loan ≈ $650–700 at 6–7% on a 30-year. Quick sanity check on any quoted payment without opening a calculator.
- $100/month extra typically shaves 4–5 years off a 30-year loan. Deciding whether the extra payment is worth it. Almost always yes at today's rates.
- 0.25% rate difference on a $400K loan ≈ $66/month and $24K total interest. Rate-shopping. A free 0.25% reduction is the equivalent of a $24K cash discount, paid out over 30 years.
- Refinancing usually pays off if you'll stay 3+ years and the rate drop is ≥0.75%. Considering a refi. Below that drop, closing costs eat the savings before you break even.
Examples
$350,000 at 6.75% over 30 years
On a $350,000 loan at 6.75% over 30 years, the monthly principal-and-interest payment is about $2,270. Over the full term you'll pay roughly $467,200 in interest — more than the loan itself. That's the cost of stretching the repayment out over three decades.
Same loan with $200/month extra
Adding $200 a month to that same loan pays it off in about 24 years instead of 30 and saves roughly $96,000 in interest. The extra is small in monthly terms but compounds aggressively because it permanently removes future interest from the loan.
Frequently asked questions
Does this calculator include taxes, insurance, and PMI?
No — this calculator shows principal and interest only (P&I). Property taxes, homeowners insurance, and PMI are separate line items handled by your lender as part of an escrow account, and they vary widely by location and lender. Your full PITI payment can easily be 25–40% higher than the P&I figure shown here.
How much does a quarter-point change in rate actually cost?
On a $400,000 30-year loan, going from 6.50% to 6.75% raises the monthly payment by about $66, and adds roughly $24,000 in total interest paid across the life of the loan. The lesson: small rate differences are worth rate-shopping. A free 0.25% point reduction is the equivalent of a $24,000 cash discount, paid out over 30 years.
Should I make extra payments or invest the difference?
It depends on your mortgage rate vs. your expected investment return. At low fixed rates (3% and below), most savers come out ahead investing the extra. At higher rates (6%+), a guaranteed risk-free "return" equal to your interest rate is genuinely competitive with stock-market expected returns — and it's tax-advantaged, since the savings aren't taxable. Run the math both ways before deciding.
Why do early payments go almost entirely to interest?
Interest each month is calculated on the remaining balance. At the start the balance is highest, so the interest charge is highest. Whatever's left of your fixed monthly payment after interest goes to principal — which is a small amount early on. As the balance shrinks, interest shrinks too, and the principal share grows. This pattern is called amortization, and it's why extra principal payments at the start of the loan have an outsized effect.