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Loan Amortization Calculator
Calculate a full loan amortization schedule with principal, interest, remaining balance and optional extra-payment impact.
Use this calculator to build an amortization schedule showing how each loan payment is divided between principal and interest over time.
You can also model optional extra payments to estimate how they may affect payoff time and total interest.
The periodic rate is the nominal annual rate divided by 12, 26 or 52 payments per year. Fractional payment counts round up and that whole count is used in the formula. No daily accrual, Canadian mortgage semi-annual compounding or lender-specific conventions are modeled. The dollar sign is generic; use one currency throughout.
Calculations run locally in your browser. Your financial inputs are not saved.
Enter your loan assumptions.
About this calculator
Example: $25,000 Loan Over 5 Years
Static example, not a result calculated from your current inputs: a $25,000 loan at 7% over 5 years with monthly payments uses a periodic rate of 0.07 ÷ 12 and 60 scheduled payments.
- Scheduled payment: approximately $495.03.
- First payment interest: $145.83; principal: $349.20; ending balance: $24,650.80.
- Total interest: approximately $4,701.80; total repayment: $29,701.80.
- All calculations retain full precision. Displayed currency values are rounded to cents.
Example: Zero-Interest Loan
Static example: a $12,000 loan at 0% over 2 years with monthly payments has 24 payments of $500. Each payment is $500 principal and $0 interest; total interest is $0.
How the Schedule Works
The model calculates interest from each period’s opening balance, applies the payment, and carries the unrounded ending balance into the next period.
- The standard payment is P × r ÷ (1 − (1 + r)^(−n)); at 0% interest it is P ÷ n.
- Recurring and one-time extras are modeled at the selected payment frequency. Any final payment is capped at the remaining balance plus that period’s interest.
- Yearly summaries group monthly, biweekly and weekly payments into 12-, 26- and 52-payment periods.
- No loan start date is used, so payoff durations are not exact calendar dates.
- Displayed schedule amounts are rounded; totals and subsequent calculations use unrounded values.
Frequently asked questions
What is loan amortization?
Amortization is the repayment of a loan through scheduled payments that cover interest and reduce the principal balance over time.
Why does more of the early payment go to interest?
Interest is calculated from the remaining balance. When that balance is larger, interest can take a larger share of a payment. As principal falls, the interest portion generally becomes smaller.
How is an amortization schedule calculated?
The model divides the nominal annual interest rate by payments per year, calculates the standard payment, then calculates each period’s interest, principal and ending balance. At 0% interest, the payment is principal divided by the number of payments.
How do extra payments affect a loan?
In this model, extra payments reduce principal and can shorten payoff time or reduce total interest. Actual loan terms may include prepayment restrictions or charges that this calculator does not model.
Why might lender schedules differ from this calculator?
Fees, payment dates, compounding conventions, daily interest accrual, rounding and loan-specific terms can change an actual lender schedule.
What is the difference between this calculator and the Loan Payment Calculator?
Loan Payment Calculator focuses on quick payment and comparison estimates. Loan Amortization Calculator provides the period-by-period repayment schedule and principal/interest breakdown, including recurring and one-time extra-payment scenarios.
This calculator provides general planning estimates only and is not financial, lending, tax or legal advice. Actual lender calculations may differ because of fees, compounding conventions, payment timing or loan-specific terms.