Amortization Calculator: Visualize Loan Payments & Interest Over Time

How to use the tool

• Loan Amount: Type the sum you intend to borrow—try $180 000 or $320 000.
• Annual Interest Rate: Enter a yearly rate such as 4.2 % or 6.1 %.
• Loan Term (years): Choose the repayment horizon, e.g., 15 or 25 years.
• Payment Frequency: Pick monthly, bi-weekly, or weekly; more frequent payments trim interest faster.
• Start Date (optional): Set the first-payment date to build a dated schedule.
• Press Calculate. The widget displays your periodic payment, total interest, total outlay, a payment-by-payment table, and a line chart of principal, interest, and balance.

Behind the numbers

The calculator applies the standard amortization formula:

$$ \text{Payment}=rac{r \times P}{1-(1+r)^{-n}} $$

• P = principal
• r = periodic interest rate (annual rate / payments per year)
• n = total number of payments

Example A

$180 000 at 4.2 % for 25 years, paid monthly (12×/yr):

$$ r=rac{0.042}{12}=0.0035,\; n=25\times12=300 $$ $$ \text{Payment}=rac{0.0035\times180\,000}{1-(1+0.0035)^{-300}}\approx \$969.23 $$

Example B

$320 000 at 6.1 % for 15 years, paid weekly (52×/yr):

$$ r=rac{0.061}{52}=0.001173,\; n=15\times52=780 $$ $$ \text{Payment}=rac{0.001173\times320\,000}{1-(1+0.001173)^{-780}}\approx \$626.70 $$

Quick-Facts

• Average U.S. 30-year fixed mortgage rate was 6.90 % in May 2024 (Freddie Mac PMMS, 2024).
• Switching to bi-weekly payments can cut a 30-year term by roughly 4 years (CFPB, 2023).
• Canadian mortgages default to a 25-year amortization (CMHC “Homeowner Mortgage Loan Insurance”, 2023).
• The total interest on a $250 000 loan at 4 % over 30 years is about $179 674 (CFPB Mortgage Calculator, 2024).

FAQ

What does the calculator show?

It returns your exact periodic payment, cumulative interest, total cost, and a payment-by-payment breakdown that tracks principal, interest, and remaining balance (CFPB, 2024).

How are payments computed?

The tool solves the amortization equation using the periodic rate derived from your annual rate and chosen frequency, ensuring equal payments that fully repay the loan by term-end (Federal Reserve Consumer Guide, 2023).

Can extra payments reduce interest?

Yes. Any amount applied directly to principal lowers the balance immediately, shrinking future interest charges; one extra monthly payment per year can save thousands (CFPB, 2023).

Why do early payments contain more interest?

Interest accrues on the current balance; at the start, the balance is highest, so the interest portion dominates until principal diminishes (Investopedia “Amortization”, 2024).

Does changing payment frequency alter total cost?

More frequent payments shorten the compounding interval, reducing interest. Weekly payments on a 6 % loan save roughly 2 % of total interest versus monthly, assuming the same annual outlay (Bank of Canada Calculator, 2023).

Are bi-weekly and semi-monthly identical?

No. Bi-weekly means 26 payments per year, generating one extra monthly equivalent; semi-monthly means 24 payments, matching the monthly total (CFPB, 2023).

How accurate is the schedule?

The calculator assumes fixed rates and on-time payments. Variable-rate loans or late fees will alter actual results; always confirm with your lender (Freddie Mac “Understanding ARM”, 2023).

Can I export the amortization table?

Click “Download CSV” in the interface to save the full schedule for spreadsheets or financial planning software (Tool Help Guide, 2024).

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