Amortization Schedule Calculator

Understanding an amortization schedule

An amortization schedule is a month-by-month table that shows how each payment is split between interest and principal. It also tracks the remaining balance after each payment. For fixed-rate loans, the payment is usually constant, but the mix of interest and principal changes over time.

The schedule is useful for planning because it makes the cost of borrowing transparent. You can see how much interest you pay in the early months, how quickly your balance declines, and how much interest you avoid when you make extra payments.

This tool is designed for clarity: it shows the full schedule and a clean balance chart so you can connect the numbers to the payoff timeline.

How to read the schedule table

Each row represents one month. The “Payment” is the amount applied that month, “Interest” is the charge for borrowing (based on that month’s starting balance), and “Principal” is the part that reduces the balance. The ending “Balance” is what remains after the principal portion is applied.

The important insight is that interest is not a fixed dollar amount. Even if the payment stays the same, interest declines as the balance declines. That means principal increases over time, which is why the balance curve is slow at first and faster later.

Extra payments and early payoff

Extra monthly payments typically apply to principal. Paying down principal earlier reduces the base on which interest is calculated in every future month. Over long terms, this can reduce both total interest and the number of payments.

When you add an extra payment, compare the new payoff months to the original term. The difference is “time bought back.” For many borrowers, the value of extra payments is not just interest saved, but also flexibility: you can choose to stop extra payments later if your cash flow changes.

Where schedules differ in real life

Real lenders may compute interest daily, handle partial months differently, and round to the nearest cent. Some loans have escrow, fees, or adjustable rates that change the payment over time. Those details can make a real statement differ slightly from a simplified schedule.

Even with those caveats, the schedule is extremely useful. It explains the direction and magnitude of the trade-offs. Use it as a decision-making tool, then confirm exact terms with your lender or official loan documents.

Using the schedule for better decisions

A schedule helps you answer practical questions: When will the balance fall below a certain threshold? How much interest will I pay in the next 12 months? What happens if I add a small extra payment? These questions matter for refinancing, budgeting, and planning.

If you plan to sell the asset or refinance before the loan ends, focus on the balance at your expected exit month and the interest paid up to that point. Total interest over the full term may be less relevant if you do not keep the loan for the full duration.

For financial planning, clarity beats precision. The schedule is a transparent model that makes trade-offs visible and supports better choices even when real-world details differ slightly.