Amortization Calculator
Amortization is how a fixed loan payment splits between interest and principal each month. Early on it is mostly interest; over time more goes to principal until the balance hits zero. This calculator gives the payment, total interest and a full schedule.
Use this amortization calculator for any fixed-rate loan — mortgage, auto, personal or student. Enter the amount, rate and term, and it returns the monthly payment, the total interest, and a complete amortization schedule you can view year by year or month by month.
Enter the loan amount, rate and term, then press Calculate to see the payment, total interest and schedule.
How the amortization calculator works
Amortization is the quiet engine behind almost every loan. Your payment stays the same each month, but what it does changes constantly. The lender charges interest on whatever you still owe, so at the start — when the balance is largest — most of your payment is swallowed by interest and only a little chips at the principal. Each month the balance is a fraction smaller, so a fraction less interest is due, and a fraction more of your fixed payment goes to principal. This calculator runs that process to the end and lays out every step.
The schedule makes the pattern visible: watch the interest column shrink and the principal column grow, year after year, until the balance reaches zero. Because the same math governs every fixed-rate loan, you can use it for a mortgage, an auto loan or a personal loan alike. And if you want to see how overpaying rewrites the schedule, the extra payment calculator shows the years and interest it saves.
The amortization formula
The fixed payment comes from the standard amortization formula:
then each month splits like this:
- P — loan amount
- i — monthly rate = annual rate ÷ 12
- n — number of payments = years × 12
Reading the schedule
Two habits make the schedule genuinely useful. First, compare the first year to the last. On a long mortgage, the principal paid in year one is tiny next to year thirty, even though the payment never changed — that gap is the cost of borrowing laid bare, and it is why building equity feels glacial at the start. Second, look at the total interest. Over a 30-year term it can approach or exceed the amount you borrowed, so a lower rate or a shorter term is worth far more than it first appears. The annual view is best for spotting these patterns; the monthly view is there when you need the exact figure for a specific payment.
Using it beyond mortgages
Any loan with a fixed rate and level payment amortizes the same way, so this tool doubles as an auto-loan, personal-loan or student-loan schedule. The only things that change are the amount, rate and term. Seeing the split is especially eye-opening on shorter loans, where principal ramps up quickly, and on high-rate debt, where the interest column stays stubbornly large — a strong argument for paying such loans down first. Whatever the loan, the schedule turns an abstract monthly payment into a clear map of where your money actually goes.
Amortizing, simple-interest and negative-amortization loans
Not every loan behaves like the standard schedule above. A conventional amortizing loan — what this calculator models — charges interest on the remaining balance each period and keeps the payment level until the balance is gone. A simple-interest loan is similar but accrues interest daily on the balance, which many auto and personal loans do; the practical difference is timing, since paying a few days early sends slightly more to principal and paying late costs slightly more interest. A negative-amortization loan is the one to watch: if the required payment is less than the interest due (as can happen with some option-ARMs or deferred plans), the shortfall is added to the balance, so what you owe actually grows over time. A balance column that falls steadily is healthy amortization; a rising balance is the warning sign of negative amortization. For loans that amortize but end in a lump sum, see the balloon loan calculator.
Estimate only — not financial advice. Assumes a fixed rate and level payments; your actual loan may include fees, escrow or a variable rate. Confirm figures with your lender.
How to use it & key terms
Enter the loan amount, rate and term, then press Calculate to see the payment, total interest and the schedule. Switch between the annual and monthly views.
| Term | What it means |
|---|---|
| Amortization | Paying off a loan through regular payments of principal and interest. |
| Principal | The part of a payment that reduces the balance. |
| Interest | The part of a payment that is the cost of borrowing. |
| Balance | The amount still owed after each payment. |
| Schedule | The table of every payment's split and remaining balance. |
| Total interest | The sum of all interest paid over the loan. |
Sources & methodology
The calculator computes the level payment from the standard amortization formula, then builds the schedule month by month: interest each month equals the outstanding balance times the monthly rate; principal is the payment minus that interest; and the balance falls by the principal. Months are grouped into calendar years for the annual view. Totals sum the interest and principal across every payment. It assumes a fixed rate, level payments and no fees or escrow.
Sources: Standard loan amortization formula and a month-by-month principal-and-interest schedule.
Why refinancing restarts the amortization clock
One detail the schedule above quietly reveals is that amortization always begins again from zero. When you refinance an existing loan, the lender does not pick up where your old schedule left off — it writes a brand-new one. That fresh schedule is front-loaded with interest in exactly the same way the original was, because the balance is once again at its highest point relative to the payments still ahead of it. So even a lower interest rate can end up costing more if it arrives attached to a full-length new term. It is one of the most common surprises for borrowers who assume a refinance simply swaps one rate for another.
Picture someone a decade into a thirty-year loan. They have finally reached the stretch of the schedule where a healthy share of every payment attacks principal and the balance falls in visible steps. If they refinance into another thirty-year loan, they reset to month one — back to the interest-heavy beginning where progress crawls. The monthly figure often drops, which feels like a clear win, but the finish line has been pushed years into the future, and the total interest paid can climb despite the better rate. The rate is only half the picture; the remaining term is the other half.
The practical habit is to compare the interest left on your current loan against the interest on a new one over the years you actually intend to stay, rather than judging the two rates in isolation. If you do refinance, you can match the new term to the time left on the old loan, or keep overpaying the new loan to protect your original payoff date. An alternative that never resets the schedule at all is a recast: you make a lump-sum payment and the lender re-amortizes the same loan across its remaining term, so the rate and payoff date stay put while the payment eases. You can explore that route with the mortgage recast calculator.
Before you refinance, it helps to weigh a few things side by side:
- The total interest remaining, not just the headline rate.
- The new term — a longer one can quietly erase the savings.
- Closing costs, which restart alongside the schedule.
- Whether recasting or overpaying would reach the goal more cheaply.
Run your remaining balance through the calculator above as if it were a brand-new loan, and the reset schedule becomes clear before you ever sign.
Frequently asked questions
What is an amortization schedule?
A table showing every payment on a loan, split into interest and principal, with the remaining balance after each. It reveals how a fixed payment shifts from mostly interest at the start to mostly principal near the end, and when the loan is repaid.
How is amortization calculated?
Each month, interest is charged on the balance (balance × annual rate ÷ 12). The rest of your fixed payment reduces principal. The lower balance means slightly less interest next month, so a little more goes to principal — repeating until the balance is zero.
Why is early payment mostly interest?
Because interest is charged on the balance, which is highest at the start. Early on, most of your payment is interest and little reduces principal. As the balance falls, the interest portion shrinks and the principal portion grows.
Does this work for any loan?
Yes. The same math applies to mortgages, auto, personal and student loans — any fixed-rate loan with a level payment. Enter the amount, rate and term, and the schedule and totals apply regardless of loan type.
How do extra payments change the schedule?
Extra payments go straight to principal, shrinking the balance faster, which cuts both the number of payments and total interest. This shows the standard schedule; to model extra payments, use the extra payment or payoff calculator.
What is the difference between the payment and the interest?
The payment is the fixed amount you send; the interest is only the part consumed by the loan's interest charge, with the rest going to principal. Early payments are mostly interest, so the split shifts over time while the payment stays the same.
What is total interest on a loan?
The sum of the interest portion of every payment — the extra you pay above what you borrowed. On a long mortgage it can rival or exceed the loan amount, which is why the rate and term matter so much.
Can I see a yearly instead of monthly schedule?
Yes. Use the Annual view for a compact year-by-year summary, or switch to Monthly to see every payment. Annual is easier to scan; monthly is useful for tracking a specific payment or detailed records.
What is the difference between amortization and simple interest?
An amortizing loan charges interest on the outstanding balance and keeps the payment level, shifting each payment from interest toward principal over time. A simple-interest loan accrues interest daily on the balance, which many auto and personal loans use. The math is close, but with simple interest the day you pay matters — paying early sends a little more to principal, paying late adds a little more interest.
What is negative amortization?
It happens when your payment is smaller than the interest due, so unpaid interest is added to the balance and what you owe grows rather than shrinks. It can occur with some option-ARMs or deferred-payment plans. It is the opposite of a normal amortizing loan, where the balance falls every month — a red flag to understand fully before agreeing to any loan that allows it.