Enter the loan details
Start with the loan amount, annual rate, term, and payment timing. The result separates each payment into payment, principal, interest, and remaining balance, then shows the formula, assumptions, total interest, payoff time, and full payment schedule. Add an extra payment per period to model additional principal.
- Enter Starting loan balance ($), Annual interest rate (%), and Loan term.
- Select Term unit, either Years or Months.
- Choose Payment schedule: Monthly (12/year), Bi-weekly (26/year), Weekly (52/year), Quarterly (4/year), or Annually (1/year).
- Enter Extra payment per period ($, optional) to add principal each period.
- Click Calculate, then choose Copy result or Download result (.txt).
Read the result
After Calculate, Result shows Scheduled payment / period, Total interest paid, Total of all payments, and Payoff time. The assumptions table records the payment frequency, entered term, periodic interest rate, extra payment, and actual periods to payoff. Full payment schedule lists Payment, Principal, Interest, and Remaining balance for each period.
Starting loan balance: $200,000
Annual interest rate: 6%
Loan term: 30 Years
Payment schedule: Monthly (12/year)
First period: $1,199.10 payment, $1,000.00 interest, $199.10 principal
Remaining balance after period 1: $199,800.90How the payment and interest are calculated
The calculator turns the annual rate into a periodic rate with r = Annual rate / 100 / Periods per year. For a rate above 0%, the scheduled payment uses Payment = Balance x r / (1 - (1 + r)^-n). At 0%, it uses Balance / n. Each period then calculates Interest = Remaining balance x r and Principal = Payment - Interest.
Years stay in years. Months are divided by 12, multiplied by the selected periods per year, and rounded to a whole period. Starting loan balance ($) and Loan term must be greater than 0. Annual interest rate (%) must be between 0 and 100. The term and schedule must produce 1 to 4,800 periods. A blank Extra payment per period ($, optional) is 0; a negative or non-numeric entry causes an error.
What an extra payment changes
Extra payment per period ($, optional) is added to the scheduled payment and applied entirely to principal. If the remaining balance is smaller than the scheduled payment plus the extra amount, the final payment is reduced to the amount needed to reach zero. The schedule can therefore contain fewer periods than the original term.
Scheduled payment: $1,199.10
Extra payment per period: $100.00
First period: $1,299.10 payment, $299.10 principal
Remaining balance after period 1: $199,700.90Compare payment schedules
Run the same balance, rate, and term with Monthly (12/year) and Bi-weekly (26/year) to compare payment count, interest totals, and payoff time. Weekly (52/year), Quarterly (4/year), and Annually (1/year) use their own periods-per-year values.
An extra amount per period shows how the balance changes when more principal is paid. Inspect the principal and interest split before choosing Copy result or Download result (.txt).
Choose another calculator for different inputs
Use this calculator for a principal-and-interest schedule built from a balance, rate, term, and payment frequency. Choose the Loan Calculator for total cost and an optional origination fee. Choose the Mortgage Calculator for a fixed-rate mortgage with taxes, insurance, HOA, mortgage insurance, or extra principal scenarios. Choose the Auto Loan Calculator for vehicle price, down payment, trade-in, sales tax, title, and fees. The Financial Calculators category lists other loan, debt, pay, investing, housing, and savings calculators.
Frequently asked questions
What does an amortization calculator calculate?
It calculates the payment, principal, interest, and remaining balance for each payment period. It also shows the formula, assumptions, total interest, total payments, and payoff time.
How is interest calculated in a loan payment schedule?
Each period's interest is the remaining balance multiplied by the periodic rate. The principal portion is the payment minus that interest, and the balance is reduced by the principal.
How does an extra payment change an amortization schedule?
An extra payment is added each period and applied entirely to principal. The final payment is adjusted when the remaining balance is smaller than the scheduled payment plus the extra amount.
Does the Amortization Calculator use lender data?
The calculation uses the values entered in its fields. Its script does not fetch live rates, lender records, or credit data.
Why do Monthly and Bi-weekly loan payment schedules differ?
They use different periods per year, so the periodic rate, payment count, interest accrual, and balance reductions differ. The assumptions table shows the periods per year and the resulting schedule for the selected option.