1. What Is This Calculator?

This calculator simulates loan repayment with variable payment amounts each period. It's useful for loans with flexible payment schedules or when you want to model extra payments.

2. How Does It Work?

The calculator uses the following formula for each period:

Where:

• Previous Balance — Loan amount at start of period
• Payment — Payment amount for that period
• Interest Rate — Periodic interest rate (decimal)

3. When To Use It

Common uses: Modeling student loans with income-based repayment, mortgages with extra payments, business loans with seasonal payments, or any loan where payment amounts vary.

4. How To Use It

Instructions:

1. Enter the principal loan amount
2. Enter the periodic interest rate (as decimal - e.g., 0.005 for 0.5%)
3. Enter comma-separated payment amounts for each period
4. Click Calculate to see the amortization schedule

5. Frequently Asked Questions

Q1: What if my payments are irregular?
A: Just enter the exact payment amounts in order, separated by commas.

Q2: How do I model extra payments?
A: Enter your regular payment amount, then add the extra amount in the period you plan to make it.

Q3: What if I want to skip a payment?
A: Enter 0 for that period's payment.

Q4: Can I use annual, quarterly, or monthly rates?
A: Yes, just make sure your payment amounts match the period (e.g., monthly payments with monthly rate).

Q5: What happens if the balance goes negative?
A: The calculator stops when balance reaches zero or goes negative, meaning the loan is paid off.