How Fixed-Rate Loan Amortization Works
Loan amortization is the scheduled repayment of debt principal and accrued interest through regular periodic installments over a defined time horizon. Each payment is divided into an interest portion (the cost of borrowing against the current outstanding balance) and a principal portion (equity repayment that reduces the debt).
Equal Payment (Annuity) vs. Equal Principal (Linear)
- Equal-Payment Amortization (Fixed Monthly Installment): The borrower pays a constant dollar amount every month. In early periods, interest comprises the bulk of the payment; over time, as the remaining balance declines, interest drops and principal repayment accelerates until the loan reaches a zero balance.
- Equal-Principal Amortization (Decreasing Monthly Installment): The borrower pays a fixed amount of principal each month plus whatever monthly interest has accrued on the remaining balance. Installments start higher and decrease steadily, resulting in faster principal reduction and lower total interest paid over the life of the loan.
Mathematical Formulas
P_periodic = L * [ r * (1 + r)^n ] / [ (1 + r)^n - 1 ]
- L = Initial loan principal balance
- r = Periodic monthly interest rate (Annual Rate / 12)
- n = Total number of monthly installments (Term in Years × 12)
Benefits of Additional Principal Payments
Making recurring additional principal payments directly reduces the outstanding debt ahead of schedule. Because interest is computed on the remaining principal balance, extra payments compound into significant cumulative interest savings and substantially shorten the time to debt-free ownership.
Frequently Asked Questions
- ¿Cuál es la diferencia entre cuota fija y amortización constante?
- En la cuota fija (sistema francés), la mensualidad total no cambia: al principio se pagan más intereses y menos capital, invirtiéndose con el tiempo. Con capital constante (sistema alemán), amortizas la misma cantidad de capital cada mes, por lo que la cuota total decrece y se pagan menos intereses globales.
- ¿Cómo reduce el coste del préstamo amortizar capital extra cada mes?
- Las aportaciones extraordinarias mensuales reducen de inmediato el capital pendiente. Al devengarse los intereses sobre el saldo vivo, amortizar antes reduce sustancialmente el total de intereses y acorta la duración del préstamo.
- ¿Cambiar la moneda modifica los cálculos?
- No. El selector de moneda modifica únicamente los símbolos y el formato numérico local, sin aplicar ninguna tasa de conversión cambiaria a tu modelo financiero.