$
%
20%
15 yr
20 yr
30 yr
Loan amount$360,000
Down payment$90,000
Total interest$459,160
Total of payments$819,160
The split
Principal 44%Interest 56%

Balance over time

Year 030 years

The schedule

YrPrincipalInterestBalance
1$4,024$23,282$355,976
2$4,293$23,012$351,683
3$4,581$22,725$347,102
4$4,888$22,418$342,214
5$5,215$22,090$337,000
6$5,564$21,741$331,435
7$5,937$21,368$325,498
8$6,334$20,971$319,164
9$6,759$20,547$312,405
10$7,211$20,094$305,194
11$7,694$19,611$297,500
12$8,210$19,096$289,290
13$8,759$18,546$280,531
14$9,346$17,959$271,185
15$9,972$17,333$261,213
16$10,640$16,666$250,573
17$11,352$15,953$239,221
18$12,113$15,193$227,108
19$12,924$14,382$214,184
20$13,789$13,516$200,395
21$14,713$12,592$185,682
22$15,698$11,607$169,984
23$16,750$10,556$153,234
24$17,871$9,434$135,363
25$19,068$8,237$116,295
26$20,345$6,960$95,950
27$21,708$5,598$74,242
28$23,162$4,144$51,081
29$24,713$2,593$26,368
30$26,368$938$0

The formula

M=P⋅r(1+r)n(1+r)n−1M = P \cdot \dfrac{r(1+r)^n}{(1+r)^n - 1}
P — loan principal
r — monthly interest rate (annual ÷ 12)
n — number of payments (years × 12)

How it works

Fixed payments stay level, but the split shifts: interest is charged on the balance, so early payments are mostly interest and later ones mostly principal. A bigger deposit or shorter term cuts total interest sharply.

FAQ

Is PMI included?

No — with under 20% down you’ll usually pay private mortgage insurance on top of this figure.

Fixed or variable rate?

This assumes a fixed rate: the payment stays level for the full term.

How does a bigger down payment change the numbers?

A larger down payment shrinks the loan itself, which lowers both the monthly payment and the total interest — and once it reaches 20%, it typically also removes the need for PMI.

Why does a 15-year term have a much higher payment than a 30-year term?

The same loan amount is repaid over half the time, so each payment must cover far more principal, even though a shorter term dramatically cuts the total interest paid.

What is amortization and why does the chart curve the way it does?

Amortization is the process of paying down a loan through regular payments split between interest and principal; because interest is charged on the remaining balance, the split shifts steadily from mostly interest early on to mostly principal later.

Should I choose the 15-year, 20-year or 30-year option?

A shorter term saves substantially on interest but requires a higher monthly payment, so the right choice depends on how much monthly payment your budget can comfortably absorb.

How much does refinancing later change the total cost?

Refinancing resets the loan to a new rate and term, so it can lower payments or interest if rates have fallen, but it also restarts the amortization clock, which can increase the interest paid overall if done too often.

Related calculators
Refinance calculatorAffordability calculatorExtra-payment calculator

How the mortgage payment is calculated

Your monthly payment on a standard fixed-rate loan stays the same every month, but it is split between interest and principal. Interest is charged on the balance you still owe, so at the start most of the payment covers interest and only a little reduces the balance. As the balance falls, the interest portion shrinks and more of each payment goes to principal — which is why the amortization schedule accelerates over time. In symbols the monthly payment is M=P r(1+r)n(1+r)n−1M = P\,\frac{r(1+r)^n}{(1+r)^n-1}, where rr is the monthly interest rate and nn the number of payments.

What affects how much you pay

Three levers move the number most: the amount borrowed (the price minus your down payment), the interest rate, and the term. A larger down payment lowers the loan and, above 20%, usually removes private mortgage insurance. A lower rate cuts the interest charged every month. A shorter term raises the monthly payment but dramatically reduces the total interest paid over the life of the loan.

What this calculator does not include

The figure shown is principal and interest only. Property taxes, homeowners insurance, HOA dues and mortgage insurance are billed separately and vary by location and lender, so budget for them on top of the payment shown here.